River Water Salinity Research Articles

ЗАСОЛЕННЯ РІЧКОВИХ ВОД В УМОВАХ УРБОЛАДШАФТНОЇ ГЕОСИСТЕМИ І ПОТЕПЛІННЯ КЛІМАТУ

Purpose. The growth of surface water salinity in urban landscapes due to both anthropogenic factors and gradual global climate change is studied. The influence of various factors is analyzed, according to the data that have been published in recent years. Methodology. Statistics on the state of surface waters, acidity of precipitation and the quality of drinking water in Ukraine show that in the southern and south-eastern regions the situation is becoming threatening. As Kharkiv region is one of the three leaders in the demands for drinking and technical water among the regions of Ukraine, the analysis of water sources in the Kharkiv region is carried out. Results. The results of measurements of chemical parameters of water samples from different parts of the river system Kharkiv-Lopan-Uda in Kharkiv: at the entrance of each river into the city, at industrial sites, at the mouth and at the exit of the river Uda from the city. It is shown that in recent years there has been a steady increase in the total concentration of salts. The rivers Kharkiv, Lopan and Udy at the entrance to the territory of Kharkiv have a fairly low content of sulfates, chlorides, magnesium and calcium, but after the passage of industrial areas to the city center there is a significant increase in salinity and water hardness. Our own data are in good agreement with the results of water quality tests by other laboratories. Thus, in the context of global climate change, the salt content in the river system Kharkiv-Lopan-Uda increases, which significantly affects the system of groundwater and drinking water. Originality. In the research the detailed data on concentrations of the ions Cl-, SO42-, Са++, Mg++ in 12 locations along the three rivers (Kharkiv, Lopan, Udy) of the complex river sys- tem in different seasons (spring, summer, autumn) have been studied and compared to similar data from open sources. The statistical dependencies of the relative concentrations during the last 40 years have been analyzed. Practical meaning. It is determined that the concentrations of some ions demonstrate the monotones growth during the last years, while others varies non-monotonously. Therefore, the influence of different natural and antropogenic factors on global gradual increase in the river water salinity can be quantified by a complex index weighted over a set of concentrations. Conclusions. The results of the literature and measurement data analysis confirmed that with increasing anthropogenic factors and global climate change, the level of surface and groundwater in the urban area of Kharkiv region will decrease and their quality will deteriorate due to increased salinity, calcification and levels of a number of pollutants, which requires further detailed study of this complex problem, permanent data monitoring and systematization in the open access sources of information, which can be processed both by statistical methods and with the help of new system dynamic approaches for the dynamical systems with the ability to control and stabilize the system.

Design and Implementation of an IoT-based River Water Salinity Monitoring System Using MSP432

The drought and salinity intrusion in the Mekong Delta in the years has become more and more serious, but in this region, the system automatically measures and collects water salinity data at either the river mouths or the canal has not been deployed and used widely due to the high investment cost. The goal of this study is to design a monitoring and data acquisition on river water salinity based on the IoT (Internet of Things) technology. The sensor nodes are designed by using the Texas Instruments MSP432 microcontrollers to read data from sensors such as water level, temperature, and salinity. This information is encapsulated and then send to a gateway via a LoRa network. The gateway uses the Raspberry Pi 3 B+ board allowing to receive the data from the sensor nodes and upload data to the cloud server through the Internet connection. A webpage is designed to offer everyone to observe measured parameters rapidly so that the people can take a proactive plan to take water for domestic use and production activities. An experiment to evaluate the performance of our proposed system was carried out in Soc Trang province, Mekong Delta, Vietnam with initial positive results.

Monitoring saline intrusion in the Ayeyarwady Delta, Myanmar, using data from the Sentinel-2 satellite mission

Summer rice cannot be grown near the coast of the Ayeyarwady Delta, Myanmar, because of the high salinity in river water during the dry season. This means that saline intrusion should be monitored to manage the irrigated rice-growing area. The aim of this study therefore is to develop a model to estimate the salinity of river water using satellite imagery. The imagery of Sentinel-2 was suitable for monitoring saline intrusion because of their high spatial (10-m) and temporal (10-day) resolutions. We found that the reflectance of the visible bands was correlated with electrical conductivity, which was influenced by the concentration and composition of dissolved salts. When the river water mixed with the salt water from the sea, suspended particles tended to flocculate and settle, as a result, less turbid water was more saline. The best-fitting model was obtained with the green band (coefficient of determination R2 of 0.776, root mean square error of 4.896 dSm−1, and mean absolute error of 3.340 dS m−1). The saline intrusion showed considerable spatial and temporal variability during the dry season. The salinity intrusion extended approximately 80 km inland at the end of the dry season in March in the Pathein River. The 1 ppt salt concentration line in March marked the boundary between cultivated and non-cultivated areas of paddy field, which indicates that cultivable areas were strongly affected by saline intrusion. The results show that more frequent and higher resolution monitoring than before of the Sentinel-2 can support effective water resource management.

A new idea for predicting and managing seawater intrusion in coastal channels of the Pearl River, China

The prediction of inland river seawater intrusion limit and the estimation of the river discharge required for mitigating seawater intrusion are crucial for water resources management but proven to be difficult using current approaches. The objective of this study is to propose a new idea for predicting coastal channel seawater intrusion and for estimating river discharges required for the downstream pushing of the intrusion limits in the Modaomen channel of the Pearl River Estuary of China. Toward this end, benthic elevation and the SRTM 30 m DEM data were combined to estimate the cumulative volume of the channel (CVC) under different tidal levels. Then, a series of mathematical equations were developed to estimate the CVC portions occupied by freshwater and seawater, respectively, based on river discharges and water salinity samples from a downstream water pumping station. A case study based on historical records was performed to demonstrate the applicability and robustness of the proposed CVC-based approach. Results indicated that the CVC-based estimates of upstream limits of the seawater intrusion agreed well with the observed data (differences <20%). Moreover, the proposed methods were able to efficiently and accurately estimate the river discharge required to push an intrusion limit downstream to a given distance. Overall, the novelty of this study is to link the channel volume with the prediction and mitigation of coastal channel inland seawater intrusion.

Causes and consequences of environmental degradation along the Shatt Al–Arab River: a coupled human and natural systems (CHANS) perspective

The Shatt Al-Arab River region (SARR) in Iraq was an economically important area for food production. By the 1970s the environment of this region had begun to deteriorate, and since then the SARR has suffered from severe human- and natural-induced problems. In this study we use a coupled human and natural systems (CHANS) perspective to identify these problems, their interconnections, and the degree to which human or natural systems have contributed to environmental degradation. We used several measures of ecological, economic and social systems to quantify the problems and document changes over the past five decades. The SARR has experienced significant climatological changes from 1975 to 2017, including lower precipitation and humidity, and increases in temperature and sea level, which affected the salinity of groundwater and river water. Human systems in the SARR also experienced tremendous stresses, including war and economic sanctions. We calculated and analyzed changes in vegetation via NDVI classification of Landsat imagery for five dates between 1975 and 2017 to understand how the environment has been affected. Changes in climatological variables were associated with lower NDVI throughout the region. However, vegetation decreased on the Iraqi side of the river, while it increased slightly on the Iranian side. This drop appears related to higher salinity in both surface and groundwater in Iraq, while irrigation from less saline water has maintained more consistent vegetation in Iran, suggesting that hydrologic diversion may be driving distinct trajectories for land use and vegetation on either side of the Shatt Al-Arab River.

Impact Study of Impoundment of the Three Gorges Reservoir on Salt-Water Dynamics and Soil Salinity in the Yangtze River Estuary

As the largest hydropower project in China, the impact of the Three Gorges Project (TGP) on the ecological environment has aroused public attention and has been studied from various aspects. After the TGP was operated, seasonably adjusted runof f by the Three Gorge Reservoir (TGR) might cause great changes of hydrological regime in the lower reaches of the Yangtze River, especially the estuarine areas where seawater intrusion is strong and salt-water environment is complicated. The salt-water dynamics in this region will be greatly influenced in response to the operation of TGP. In order to study the impact of the project on salt -water dynamics and soil salinity, a field experiment has been carried out in the Yangtze River Estuary (YRE). This paper seeks to investigate the influence of the TGR on salt-water dynamics and soil salinity in YRE through the analysis of the relationship between the impact factors of salt - water dynamics in the estuary area. Results showed that the estuarine runoff was closely related to the impoundment process, and the estuarine runoff was one of the most important factors that influenced salinity dynamics of water and soil in the estuary. Results showed that discharge of the TGR was affected by its water storage speed, and runoff at Datong station in the estuary was significantly correlated with the reservoir discharge. The reservoir discharge affected Datong runoff and the lag time of influence of the TGR on Datong discharge is about 8 to 9 days. Runoff at Datong station influenced the river water level in the estuary, and impact of the river runoff on the river water level was delayed around 13 days. The lag time of the influence of the impoundment process of the TGR on the estuarine water level is about 20 days. The discharge decrease of the reservoir reached 3600 m3/s during the impoundment period in 2011, and it would cause about 3500 m3/s flow decline at Datong station with 8 days lag. It will result in 15.6 cm drop in the water level and 4.26 mS/cm increase in river water electrical conductivity (EC) in the estuary, which indicated the increase risk of seawater intrusion intensity in the estuary. Significantly positive correlation between river water salinity and ground-water salinity was also observed, and influence of the river water salinity on groundwater salinity increased gradually from the river bank to the inland. Significant correlation existed between groundwater salinity and soil salinity in different soil layers, with the closest relation in the deep layers. Monitoring results showed that salinity of river water, groundwater and soil under impoundment process performed higher than that of non-impoundment process, and it could be inferred that the impoundment process has a certain impact on the salt-water dynamics and soil salinity in the estuary. In summary, soil and groundwater salinity were affected by the TGR, and risk of soil salinization increased.

Информационная обработка данных динамики уровня речных вод при мониторинге устойчивости геотехнической системы

Introduction. During the operation of urban and rural geotechnical systems, the mechanical indicators of the stability of the soil base are significantly influenced by the regime and dynamics of the physicochemical properties of nearby water bodies, caused by the development of karst-suffusion processes. The results of information analysis of data on the dynamics of the river runoff level and water salinity make it possible to increase the accuracy of predictive estimates of the loss of stability of the geotechnical system due to the development of karst-suffusion processes. Goals and objectives. The aim of the work is to improve the safety of operation of geotechnical systems and increase the efficiency of modeling and forecasting systems for geodynamics by developing an algorithm for assessing changes in the risk of developing suffusion processes based on an analysis of the dynamics of the level of groundwater and surface waters. Methods. The paper analyzes the data on the number of karst sinkholes depending on the dynamics of the river water level, obtained on the basis of statistical sources and reports on regime observations, as well as a result of field research. In the course of data processing, a spline interpolation method was used, an algorithm and a neural network for predicting a failure using the Bayesian regularization method based on a network training function was developed, which updates the weight and bias of the value in accordance with the Levenberg-Marquardt optimization. Results and its discussion. Based on the results of practical use, the effectiveness of the developed algorithm was confirmed in identifying the dynamics of the formation of dips during information processing of data on changes in the water level in the Oka River and data on the appearance of new dips in the period from 2012 to 2019. Conclusion. The results obtained in the work make it possible to judge the presence of the expediency of using the developed algorithm for assessing the occurrence of karst sinkholes when monitoring the stability of geotechnical systems and assessing the safety of their operation in general. Prospects for further work are associated with expanding the set of training data and adapting the structure of the neural network to the individual characteristics of the territories by introducing additional geological, hydrological and climatic parameters into the processing. Key words: geotechnical system, stability, karst sinkhole, bifurcation parameters, information processing of data.

ИССЛЕДОВАНИЕ ТРАНСФОРМАЦИИ ХИМИЧЕСКОГО СОСТАВА ПОВЕРХНОСТНЫХ ВОД С ИСПОЛЬЗОВАНИЕМ МОДЕРНИЗИРОВАННОЙ КЛАССИФИКАЦИИ АЛЕКИНА

Climatic changes and value of anthropogenic load of watershed of the rivers can be main reasons. The article researched long-term changes in the chemical composition of rivers in Ukraine. Long-term changes in the chemical composition of the river waters of Ukraine were analyzed using the modernized Alekin classification (modernization was proposed by V.K. Khilchevskyi and S.M. Kurylo). The additions introduced by the authors to the basic classification of O.A.Alekin allow fixing the dynamics of changes in the chemical composition of natural waters by cations at the group level, as well as at a more detailed level, revealing quantitative changes in the relative content of class-forming anions (at the level of subtypes). Taking it into account for the most relevant tasks which arise for hydrologists and hydrochemicals are considered to be determination of modern regularities of streamflow and hydrochemical regime in conditions of warming which happens and assessments of such changes for the perspective. The mineralization of water and concentration of the main ions in river waters change for many reasons. Studying has been executed on the Udaj river, Tur`ya river, Sula river. The trend of increasing salinity of river water is detection. Main changes are taking place in the spring. During period of supervisions there was growth of mineralization of water: Sula – from 440 to 1125 mg/dm3.The main factor there is an increased part of groundwater flow. In favor of this conclusion the following results of researches serve. The special executed calculations showed dependence between part of ground flow and chemical composition of water of the rivers. Different classifications are used to systematize natural waters by chemical composition. Attempts to classify water in accordance with the general conditions by which their chemical composition is formed are known. For analysis of long-term changes of the hydrochemical regime in different phases of the water was found and application of the classification of Alekin (modernizated). Modernization does not touch the highest trait – class, but concerns groups and types, with the introduction of a new taxon – subtype. Modernization to the basic classification of Alekhin allow to fixed in detail the dynamics of changes in the chemical composition of natural waters by cations at the group level. At a detailed level, quantitative changes in the relative content of anions (at the level of proposed subtypes) can be fixed. Verification of the modernized classification of O.A. Alekhin, made on 25 rivers of the Dnipro river basin. Rivers are located in different environmental zones, have different anthropogenic pressure and term of observations (40 – 60 years). An attempt was made to apply the modernized classification to other types of natural waters – groundwater and atmospheric.

River Water Salinity Impact on Drinking Water Treatment Plant Performance Using Artificial neural network

The river water salinity is a major concern in many countries, and salinity can be expressed as total dissolved solids. So, the water salinity impact of the river is one of the major factors effects of water quality. Tigris river water salinity increase with streamline and time due to the decrease in the river flow and dam construction from neighboring countries. The major objective of this research to developed salinity model to study the change of salinity and its impact on the Al-Karkh, Sharq Dijla, Al-Karama, Al-Wathba, Al-Dora, and Al-Wihda water treatment plant along Tigris River in Baghdad city using artificial neural network model (ANN). The parameter used in a model built is (Turbidity, Ec, T.s, S.s, and TDS in) to predict the salinity TDSout. Results showed that the effectiveness of the artificial neural network model to predicting the salinity is a good agreement between observed and the predicted value of the TDS, through the determination coefficient of the model is (0.998, 0.966, 0.997, 0.998, 0.996, and 0.996) for Al. Karkh, Sharq Dijla, Al.Karama, Al.Wathba, Al.Dora and Al.Wihda respectively. From this value can be shown that ANN is a successful tool for predicting the nonlinear equation of the salinity under different and complicated environmental case along the river.&#x0D;

Linkage of sulfur isotopic enrichment to sulfur and arsenic release in the coastal aquifers of southwestern Taiwan

High arsenic concentration in groundwater is influenced by redox reactions in As-bearing iron (oxy)hydroxide minerals and elevated total organic carbon, resulting in arsenic contamination and enrichment in groundwater after introduction of seawater into an aquifer. In this study, hydrochemical and isotopic (S, O and C) techniques were used to relate arsenic contamination and seawater flooding/intrusion in groundwater aquifers in the Chianan Plain, southwestern Taiwan. Thirty-three samples (30 from groundwater and 3 from river water) were collected from April–June of 2014. Most of the groundwater samples collected from the Chianan Plain were dominated by As(III), indicating that reducing conditions prevailed within the aquifers. The δ18O-δD plots of most of the groundwater samples from the Chianan Plain are generally lined on the global meteoric water line (GMWL), but the δ18O and δD isotopic compositions of the river water samples show enriched signals. Salinity and sulfate concentrations of river water and shallow groundwater have been found to increase after seawater flooding/intrusion. The δ18O and δD isotopic compositions of the river water showed a gradual trend toward those of seawater. The trend in the isotopic compositions of the river and groundwater samples indicated a mixing of seawater and meteoric water. Up to the present, the groundwater levels in the coastal areas of the Chianan Plain have dropped to zero meters in elevation parallel to sea level due to excessive groundwater withdrawal, resulting in seawater intrusion into the aquifers in Budai, Yichu, and Beimen in the Plain. Moreover, high salinity (48.1‰) occurred only in the Beimen 2B shallow groundwater at a depth of 60 m is a result of seawater flooding infiltration from the nearby salinized Pachang River. The δ34S[SO4]/δ18O[SO4] isotopic ratios (2.63–2.82) of low-As (concentration < 50 μg/L) river water samples were similar to those of marine sulfate minerals dissolved in seawater, but were variable (0 − 2.93) among the high-As (concentration ≧ 50 μg/L) groundwater samples from the Chianan Plain. Sulfates in seawater were introduced into the coastal aquifers of the Chianan Plain under the Holocene marine transgression, wherein the mixing of paleo- and modern-sulfates due to seawater intrusion might have occurred or are occurring. The release of sulfur and arsenic (mostly arsenite) in the Chianan Plain groundwater under reducing environments indicating redox reactions in sulfates and iron (oxy)hydroxide minerals may change the isotopic (S and O in sulfate) compositions in groundwater, resulting in enrichment of δ34S[SO4] and δ18O[SO4]. Salinity can promote arsenic release in groundwater and thus enrich the δ34S[SO4] and δ18O[SO4] isotopic compositions, in which 6.0–22.8‰ δ34S[SO4] and 9.3–15.5‰ δ18O[SO4]occur in shallow fresh groundwater (depth < 60 m) but up to 27.7‰ δ34S[SO4] and 20.4‰ δ18O[SO4] occur in shallow saline groundwater, in comparison to 0‰ δ34S[SO4] and 5.4–6.5‰ δ18O[SO4] in deep fresh groundwater (depth between 60 and 318 m) and up to 38.5‰ δ34S[SO4] and 18.7‰ δ18O[SO4] in deep brackish groundwater. This study provides insights suggesting that the As-containing iron(II) minerals are oxidized to iron(III) minerals and then re-reduced to iron(II) which leads to As release.

Drought impacts on river salinity in the southern US: Implications for water scarcity

Hydrological droughts have a diverse range of effects on water resources. Whilst the impacts of drought on water quantity are well studied, the impacts on water quality have received far less attention. Similarly, quantifications of water scarcity have typically lacked water quality dimensions, whilst sectoral water uses are associated with both water quantity and quality requirements. Here we aim to combine these two elements, focussing on impacts of droughts on river salinity levels and including a salinity dimension in quantifications of water scarcity during drought and extreme drought conditions. The impact of historical droughts on river salinity (electrical conductivity (EC) was studied at 66 monitoring stations located across the Southern USA for 2000–2017. Salinity was found to increase strongly (median increase of 21%) and statistically significantly (p ≤ 0.05) during drought conditions for 59/66 stations compared to non-drought conditions. In a next step, a salinity dimension was added to water scarcity quantifications for 15 river basins in Texas. Water scarcity was quantified using data of sector water uses, water availability, river salinity levels and salinity thresholds for sector water uses. Results showed that the dominant factor driving water scarcity highly differed per basin. Increases in water scarcity were further compounded by drought-induced decreases in water availability, increases in sectoral water demands and increases in river water salinity. This study demonstrates that droughts are associated with important increases in river salinity, in addition to reduced water availability, and that both of these aspects should be considered when quantifying water scarcity. Alleviating water scarcity should therefore not only focus on increasing water availability and reducing water demands (quantity aspects), but also on improving water quality.

Desalination of brackish water for agriculture: challenges and future perspectives for seawater intrusion areas in Vietnam

Abstract This research aims to provide an overview of the seawater encroachment threat on agriculture in lowland areas and potential solutions for better practices. It was found that the Mekong river delta experiences severe impacts from climate change with more than 75% of provinces affected by seawater intrusion, of which Kien Giang, Ca Mau and Ben Tre provinces are the most influenced with 70% affected areas. The salinity of river water was observed in the range of 15–30 g/L in 2015; meanwhile, the strongest tolerated rice species reached ceiling values of 3–4 g/L. Emerging challenges were identified due to the uncertain upstream hydrological regime coupled with high levels of tide, field evaporation and water withdrawal. The development strategies of affected provinces are given on the modification of rice tolerant capacity, and modification to aquaculture in areas with high salinity, in which water purification is in urgent demand. Desalination technologies have been proposed with various innovations which are still not practical on a large scale. The desalination of seawater and brackish water by reverse osmosis, nano-filtration, electro-dialysis, ion-exchange resins, electrochemical processes and thermal distillation has been applied to agriculture. The advance reverse osmosis shows most potential because of its advances in treating performance, cost effectiveness and effective rejection of brine.

Modeling sulfur cycling and sulfate reactive transport in an agricultural groundwater system

Many irrigated agricultural areas worldwide suffer from salinization of soil, groundwater, and nearby river systems. Increasing salinity concentrations are due principally to a high water table that results from excessive irrigation, canal seepage, and a lack of efficient drainage systems, and lead to decreased crop yield. High groundwater salinity loading to nearby river systems also impacts downstream areas, where saline river water is diverted for application on irrigated fields. This paper presents a physically-based, spatially-distributed groundwater reactive transport model that simulates the fate and transport of sulfate, the principal salt ion in many salt-affected watersheds, in an agricultural groundwater system. The model, developed from the UZF-RT3D model that simulates chemical species transport in variably-saturated subsurface systems, accounts for sulfur cycling (crop uptake, organic matter decomposition, mineralization/immobilization) in the soil-plant system, oxidation-reduction reactions, including the oxidation of residual Sulfur in marine shale, and also the effect of dissolved oxygen and nitrate on sulfate chemical reduction. The model is tested at the small scale (i.e. soil profile) and at the regional scale (500km2) in the Lower Arkansas River Valley (LARV) in southeastern Colorado, an area acutely affected by salinization in the past few decades. Results demonstrate that although the major sulfate reactive transport processes are accounted for, the model consistently under-predicts measured soil and groundwater sulfate concentrations, pointing to the need for a comprehensive salinity module that accounts not only for advection, dispersion, sulfur cycling, and oxidation-reduction, but also salt ion equilibrium chemistry that includes the dissolution and precipitation of salt minerals in the soil-aquifer system. However, the model can be a useful tool to assess sulfate fate and transport in areas that are not dominated by salt mineral precipitation and dissolution.

Temporal changes in groundwater quality of the Saloum coastal aquifer

Abstract Study region Groundwater in the southern part of the Saloum Basin in Senegal. Study focus The Saloum estuary is a hypersaline and ‘inverse’ estuary where the salinity of river water increases in the upstream direction. This region is problematic in that due to the underlain superficial Continental Terminal aquifer bordered by the hypersaline estuary constitutes the unique fresh groundwater reservoir for water supply for its estimated 466,000 residents living in 18 rural districts (belonging to the regions of Fatick, Kaolack and Kaffrine). This is of high value given that the deep Maastrichtian aquifer (200–300 m depth) is saline. This study aims to describe and understand temporal changes in the chemical and isotopic compositions of groundwater, the geochemical processes and especially the groundwater salinization. New hydrological insights for the region The analytical data were discriminated into 3 groups on the basis of the water types. Na-Cl, Ca-Cl and Ca-SO4 rich waters derived from saline water intrusion at the vicinity of the Saloum River accompanied by ion exchange reactions and pollution dominate the first group. The second group located mainly in the centre and eastern parts of the region is featured fresh groundwater of Ca-HCO3 derived from calcite dissolution reactions. The third group of Na-HCO3 type and less mineralized indicates freshening processes by recently infiltrating rainwaters. Slight seasonal chemical variations are observed due to new infiltrating water reaching the water table. High variation in rainfall between the 2 reference years (2003 and 2012) also changes chemical patterns in the groundwater. Chemical evolution of the groundwater is geographically observed and is due to a combination of dilution by recharge, anthropic contamination and seawater intrusion. The results of environmental isotopes (δ18O, δ2H) compared with the local meteoric line indicate that the groundwater has been affected by evaporation processes before and during infiltration. The results also clearly indicate mixing with saltwater and an evolution towards relative freshening between 2003 and 2012 in some wells near the Saloum River.

Influence of the Po River runoff on the bacterioplankton community along trophic and salinity gradients in the Northern Adriatic Sea

AbstractThe Po River runoff strongly affects the oceanographic and ecological characteristics of the Northern Adriatic Sea. Catalysed reported deposition ‐ fluorescence in situ hybridization (CARD‐FISH) analysis was employed to assess how the composition of the coastal bacterioplankton community is influenced by the river runoff in two different seasons (spring and autumn). Samples were collected from the water column along a coastal–offshore transect in the Northern Adriatic Sea at different depths. Four clone libraries were then constructed from coastal (0 m) and offshore waters (−65 m). Higher abundances of bacteria were recorded in coastal waters as compared with the offshore samples. This result was mainly due to the trophic state of the water column, and it was related to salinity. Particularly, Actinobacteria and Gammaproteobacteria were affected by the riverine inputs, whereas Bacteroidetes and Alphaproteobacteria showed only minor responses. This was particularly clear in the autumn sample, in which a clear difference between the coastal and the offshore samples was found due to a strong influence of the less saline river water with high nutrient concentrations. Analysis of 205 partial length 16S rRNA gene sequences indicated a high diversity with the dominance of Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria mainly affiliated to coastal and marine bacterioplankton clades. Actinobacteria were also detected and, together with Gammaproteobacteria, strongly follow the freshwater intrusion. Overall, our results indicate that the seasonal difference in the Po River discharge greatly affects the bacterioplankton community. In spring we observed a smooth transition from coastal to open‐sea conditions owing to the more superficial freshwater plume. In autumn the deeper freshwater intrusion in the coastal site and thermal stratification offshore resulted in a marked difference between the coastal and offshore microbial communities.

Temporal variations of groundwater salinity and temperature in a tidal flat in front of a tide pool

A tidal flat in an estuary is a complex hydrological system, which is characterized by interactions between surface water in river and groundwater and is particularly driven by tides. Small-scale variability in the discharge or inflow could lead to variable results of surface groundwater salinity and temperature. In particular, there is a high possibility that a hydraulic head difference due to the presence of a tide pool, lagoon, or seep would cause the generation of small-scale spatial submarine groundwater discharge.This study investigates the spatio-temporal variations in surface groundwater salinity and temperature (0–50cm depth) and the groundwater table in a tidal flat in the presence and absence of a tide pool. A tide pool formed in the Ota River diversion channel at the study observation site following the construction of a masonry revetment in the intertidal zone. We established observation sites at three locations to consider the effects of the presence or absence of a tide pool. Specifically, we measured the surface water in river and groundwater salinity, temperature, and level in the presence and absence of a tide pool in 2007 and 2009. Reviewing the past data based on these results, we found the characteristic variation of groundwater salinity around the tide pool during flood event in 2004. Groundwater salinity and temperature were directly measured by setting conductivity-temperature meters in the tidal flat.We conclude that the groundwater table in the presence of the tide pool was 20cm higher than in areas where no tide pool existed. The temporal variation of groundwater salinity in the presence of the tide pool was 5psu lower than those where a tide pool was absent. Moreover, we confirmed the increase in groundwater salinity up to 8psu in the tidal flat during flood, when river water salinity was at 0psu and groundwater salinity in the tide pool was at 10psu.We consider that the high groundwater table, the low salinity, and the increase of groundwater salinity were caused by water discharge from the tide pool, and that the groundwater salinity was increased by groundwater discharge during a flood event.We expect the groundwater flow around masonry revetment has important roles of substance transportation and formation of tidal flat environment. The consideration of this phenomenon will be important for construction of artificial tidal flat and improvement of tidal flat environment.

Neural Network Modelling of Tds Concentrations in Shatt Al-Arab River Water

River water salinity is a big concern in many countries, considering agricultural and drinking usages. Therefore, prediction of amount of Total Dissolved Solid (TDS) is a necessary tool for planning and management of water resources. Shatt Al-Arab river basin in Basrah which is located in south of Iraq suffer from high salinity, therefore use of the water for irrigation and drinking has become problematic. In this regard, prediction of future TDS of Shatt Al-Arab river basin was studied using Artificial Neural Network (ANN). Data measured monthly from January 2007 up to December 2012 at monitoring station in the middle point along to the Shatt Al-Arab river has been used for training of the selected ANN. Some of water quality parameters such as, power of hydrogen (pH), Total Hardness (TH), Magnesium hardness (MgSO4), Calcium hardness (CaSO4), Chlorides (Cl), Sulphates (SO4), turbidity (TU) and electrical conductivity (EC) were considered as inputs for the ANN and Total Dissolved Solid (TDS) was the output of the model. The validation of the neural network model showed very good agreement for predictions of the TDS concentrations between observed and simulated values. The coefficient of correlation (R), during the validation process was found to be (1), and the mean squared error (MSE) was (0.075). This work supports the concept that the neural network approach is a successful method of modelling such complex and nonlinear behavior of TDS in the rivers with different environmental conditions.

Dynamics of mangrove diversity influenced by climate change and consequent accelerated sea level rise at Indian Sundarbans

Sundarbans, the largest contiguous mangrove forest of the world, regularly bears the brunt of numerous cyclones/storm surges. The frequencies of these disasters are ever increasing, in wake of the twin predicaments of sea level raise and climate change. This temporal study (2008-2013) at Jharkhali Island, delve into the dynamics of mangrove community in response to seasonal and yearly alterations in river-water salinity, due to the severe cyclone AILA (2009) and sea level raise. Raise in water salinity accentuates the abundance of salt tolerant species with physiological and phenological adaptations (Avicennia marina, Suaeda maritima) and decreased abundance of salt sensitive mangroves (Rhizophora mucronata). Exclusion of few mangrove species (Aglaia cuculata, Brownlowia tersa, Heritiera fomes, Kandelia candel and Nypa fruticans) is also evident, facilitating the proliferation of resistant, opportunistic and invasive flora (Clerodendron inerme, Derris trifoliata and Phoenix paludosa). Solutions have also been suggested in the light of the modern conservation paradigm.

Reconstructing input for artificial neural networks based on embedding theory and mutual information to simulate soil pore water salinity in tidal floodplain

AbstractSoil pore water salinity plays an important role in the distribution of vegetation and biogeochemical processes in coastal floodplain ecosystems. In this study, artificial neural networks (ANNs) were applied to simulate the pore water salinity of a tidal floodplain in Florida. We present an approach based on embedding theory with mutual information to reconstruct ANN model input time series from one system state variable. Mutual information between system output and input was computed and the local minimum mutual information points were used to determine a time lag vector for time series embedding and reconstruction, with which the mutual information weighted average method was developed to compute the components of reconstructed time series. The optimal embedding dimension was obtained by optimizing model performance. The method was applied to simulate soil pore water salinity dynamics at 12 probe locations in the tidal floodplain influenced by saltwater intrusion using 4 years (2005–2008) data, in which adjacent river water salinity was used to reconstruct model input. The simulated electrical conductivity of the pore water showed close agreement with field observations (RMSE and ), suggesting the reconstructed input by the proposed approach provided adequate input information for ANN modeling. Multiple linear regression model, partial mutual information algorithm for input variable selection, k‐NN algorithm, and simple time delay embedding were also used to further verify the merit of the proposed approach.

Particle–water interactions of platinum-based anticancer drugs in river water and estuarine water

The cytotoxic, platinum-based anticancer drugs, cisplatin, carboplatin and oxaliplatin, enter the aquatic environment largely in municipal wastes via excretion from outpatients undergoing chemotherapy. The environmental behaviour, effects and fate of these drugs are, however, unknown. In this study, the adsorption of the drugs to untreated and chemically modified (oxide-free and organic-free) sediment was examined in both river water and low salinity (S=3.2) estuarine water in order to determine the nature and extent of their interactions with suspended particles. In all cases, adsorption isotherms were linear, and the slopes of the relationships, or distribution coefficients (KDs), ranged from about 102 to 103 mlg−1. Overall, adsorption decreased in the order: cisplatin>carboplatin>oxaliplatin; in river water and: cisplatin>carboplatin, oxaliplatin; in estuarine water. There was no clear dependence of adsorption on sediment treatment but, for all sediment types, both cisplatin and carboplatin adsorption was greater in river water than in estuarine water. Qualitatively, these observations are consistent with the rates of formation of reactive, aquated degradation products and the dependencies of these rates on aqueous chloride concentration. We predict that during transport through an estuarine turbidity maximum (of suspended sediment concentration=1gL−1), up to about 45% of cisplatin and 35% of carboplatin are filtered out from the aqueous phase but that no more than 7% of oxaliplatin is retained.