A GIS mapping assessment of the suitability of the Oued Rmel aquifer for irrigation in the Zaghouan district (north-eastern Tunisia)

A total of twenty-three water samples were collected in winter 2013 to assess groundwater quality in the Oued Rmel aquifer in the Zaghouan governate in Tunisia. These samples were subject to in-field measurements of some physico-chemical parameters (temperature, pH, and salinity), and laboratory analysis of major elements. Several parameters were used to assess the quality of water destined for irrigation, including electrical conductivity (EC) and sodium adsorption ratio (SAR). As part of this work, GIS was used to study spatial distributions of SAR, EC, residual sodium carbonate, sodium percentage (%Na), Doneen’s permeability index, Kelly’s ratio, and magnesium hazard and, therefore, evaluated the water quality of Oued Rmel (good, fair, or poor) regarding irrigation. The major ions most abundantly found in the waters of Oued Rmel were in the following order: Na⁺?>?Ca²⁺?>?Mg²⁺?>?K⁺ and Cl^??>?SO₄^2??>?HCO₃. 56% of water samples from the Oued Rmel aquifer showed a low alkalinization risk, where SAR was lower than 10, 39% have a medium soil destabilization risks (10?<?SAR?<?18), and just 5% indicated high alkalinity hazards (SAR?>?26). Samples of water intended for irrigation showed a medium to high sodicity and alkalinization risk. It is expected that output may help in assessing the impacts of water quality of the Oued Rmel aquifer used for irrigation.     

Hydrogeologic effects on the quality of water in the Oued Issen watershed, western Upper Atlas Mountains, Morocco

The study of spatial and temporal variations of some hydrochemical properties in the Oued Issen watershed, Morocco, has revealed their close relation to the area's lithologic and geologic characteristics and to variations in hydroclimatological cycles. High concentrations of sodium chloride are measured during flood periods, when the outcrops of the basin are leached by streams draining the rather dense hydrographic network. These variations depend also on the relative abundance of tributaries on both sides of the Oued, their respective contributions being hydrochemically very different: (1) northern-side tributaries, which mainly leach evaporitic terranes dating from the Late Triassic and Late Liassic periods and which are rich in gypsum and halite, increase the mineralization of the Oued Issen waters flowing toward the Abdelmoumen Dam; (2) the low salinity of water observed in the upstream portion of the watershed is due to dilution by waters from the southern-side tributaries, which are derived from snowmelt and the leaching of the high Paleozoic massif; (3) in the middle part of the basin, the increase in mineralization of the Oued Issen becomes substantial between the Abdelmoumen Dam and the Dkhila Dam, the next dam downstream, due to the absence of dilution by waters from the southern-side tributaries, which are sparse in this part of the basin. In addition, during flood periods, the outflow from the first dam is stopped. Thus, the main contribution of NaCl to the Oued is from the very salty Tirkou spring, which is situated downstream from the first dam. The geological characteristics of the basin have induced the development of high-salinity zones, which are particularly evident in the southwestern part of the basin in the vicinity of the confluence of the Oued Boulebaz with the Oued Issen. The discharge of very salty springs is controlled by faults that offset the formations that underlie the hydrographic network and degrade the quality of the Oued Issen. This water later recharges the unconfined aquifer along the Oued where it flows on the Oued Souss Plain. Received, July 1998/Revised, July 1999, September 1999/Accepted, November 1999     

Study of groundwaters using the environmental tritium and hydrochemical data in the Belgrade region

A study of tritium content and some physicochemical parameters has been performed in order to investigate interconnection between surface and atmospheric waters and underground waters in Belgrade area. Samples of the precipitation at Zeleno Brdo-Belgrade meteorological station, the Danube and the Sava river water, and underground water (Ranney wells and piezometers) have been analyzed. The³H content, the content of dissolved ions, total hardness, and electrical conductivity have been measured. The tritium data show existence of two water strata in the aquifer. The upper stratum (about 16 m thick) contains older water (mean monthly³H concentration of 17 TU) and has weak interaction with the river and the precipitation. Below this stratum lies the principal water bearing stratum, strongly connected with the river with the³H concentration similar to that of surface water (mean monthly³H concentration of 50 TU) and spreading out through the entire aquifer. The contribution of the Sava river water and the two water layers at the Ranney well are calculated starting with the hydrological aquifer model, which supposes that three water components are mixed in the pumped Ranney well water. According to calculation results using the³H concentration and physicochemical characteristics as parameters, more than 70 percent of the water pumped by the Ranney well (in 1983) comes from the Sava with a time delay of less that 15 days.Properties of tritium distribution in precipitation, river waters, and underground water in the Belgrade region are established from the results of measurements of³H concentrations in the period 1976–1983.     

Origin of water salinity in a lake and coastal aquifer system

The studied area is in the Algerian Northeast. A number of interacting factors at the site are able to modify salinity. The main influences are: (1) The lithology, (2) Fedzara Lake, (3) marine waters, and (4) a prolonged drought. (1) The lithology is very clearly delineated by the outcrop of metamorphic formations (gneiss, marbles, micaschists, and quartzites) and sedimentary formations (limestones, clay, sandstones, and sands). All these formations can influence the chemical composition of waters. (2) Fedzara Lake evacuates its salted waters via the Wadi Meboudja, which connects with the Wadi Seybouse and the phreatic surface. These lake waters might induce changes in salinity. (3) The marine waters represent the third source of salinity change. Over-pumping of water from wells and drillings can cause an imbalance to the fresh–salted water interface. (4) The effects of a local prolonged drought of more than 10 years may increase water salinity. Over-pumping to augment water supply generates a fall in water levels and the drier atmosphere increases evapotranspiration. Both may contribute to increased salinity. Results of water analysis were used to observe the evolution of these various factors.     

Dangerous assemblages: Salts,trihalomethanes and endocrine disruptors in the water palimpsest of the Llobregat River,Catalonia

Water flows through time are connected to specific instances of socionatural and sociotechnical assemblages of human and non-human components. We propose the concept of “water palimpsest” in order to characterize the complex histories of chemical and metabolic alterations embodied in water flows, potentially disruptive for humans and other living beings. Through the concept of palimpsest we interpret the configuration of water flows as constantly evolving towards new patterns maintaining at the same time traces of past mixtures. In order to decipher water pollution by means of a political ecology approach we argue that it is necessary to characterize the historical contours under which certain substances in river waters appear, interact and become hazardous. Engaging critically with literature on assemblages but also with chemical and epidemiological scientific literature, and drawing from archival and oral sources, we provide an account of historically produced pollution in the waters of Llobregat River (Catalonia) by unravelling the assemblages that shape the water palimpsest in this river. In parallel, we narrate the advances in instrumentation and analysis which permitted to detect and measure substances beyond recognition by human senses and preceded legal regulations on pollutants, starting from milligrams and (thus far) arriving at nanoscales. Focusing on the emergence of three typologies of pollutants – salts, trihalomethanes (THMs) and endocrine disruptors (EDs) – we unveil how these three assemblages embody specific instances of Llobregat socioenvironmental history, pointing towards a palimpsest characterized by increasing levels of complexity and uncertainty. The concept of water palimpsest allows us to incorporate non-human agency into the analysis of water quality and to infuse political ecology with materiality and thus with a (largely missing) focus on physicochemical and biological processes.     

Coastal erosion in the south-eastern Mediterranean: case of beaches in North Tunisia

This research is conducted as part of a Spanish International Cooperation Agency project with the aim to investigate the sustainable protection of Tunisian coastal zones, as in the case of Beni Khiar and Dar Chaabane coasts (Hammamet Gulf) separated by Oued El Kebir river. The sedimentary dynamic of these beaches is studied in order to identify the main causes responsible for their erosion by the use of different approaches of in situ measurements and numerical methods. Geophysical surveys and sedimentary analyses have demonstrated that sediments are finer and less carbonated from Beni Khiar to Dar Chaabane. Then, the shoreline mapping of several missions of aerial photos has illustrated a mean shoreline retreat between 3 and 4 m/year. In terms of sand volume, a sediment loss more than 30,000 m³/year at Dar Chaabane has been observed since the hill lake structures were built within Oued El Kebir river in 1996. Finally, modelled hydrodynamic and sedimentary patterns have illustrated the refraction of waves in deep water close to shoals and a high-energy concentration along Dar Chaabane coast. The sediment transport direction is mainly of NE-SW induced by ESE-SE wave-driven alongshore current. Results provided by these approaches have shown the importance of Oued El Kebir sediment yield in supplying the neighbouring beaches. Changes in sedimentary dynamics are affected by the modification of hydrodynamic patters caused by the presence of hydrological dams and the implementations of hotels close to the shoreline. This finding underlines the key role of Oued El Kebir fluvial activity in controlling the equilibrium of beaches and their sensitivity to coastal managements induced by man activities, as in the case of the most Mediterranean beaches.     

Assessment of water quality and identification of pollution sources of three lakes in Kashmir, India, using multivariate analysis

Multivariate statistical techniques, such as cluster analysis, principal component analysis (PCA) and factor analysis (FA) were applied to evaluate and interpret the water quality data set for 13 parameters at 10 different sites of the three lakes in Kashmir, India. Physicochemical parameters varied significantly (p?<?0.05) among the sampling sites. Hierarchical cluster analysis grouped 10 sampling sites into three clusters of less polluted, moderately polluted and highly polluted sites, based on similarity of water quality characteristics. FA/PCA applied to data sets resulted in three principal components accounting for a cumulative variance of 69.84, 65.05 and 71.76% for Anchar Lake, Khushalsar Lake and Dal Lake, respectively. Factor analysis obtained from principal components (PCs) indicated that factors responsible for accelerated eutrophication of the three lakes are domestic waste waters, agricultural runoff and to some extent catchment geology. This study assesses water quality of three lakes through multivariate statistical analysis of data sets for effective management of these lakes.     

Chloride contamination in construction aggregates due to periodic saline water intrusion: a case study in the Kaluganga River Estuary, Sri Lanka

The Kaluganga River Estuary is one of the main sources of construction sand in Sri Lanka. Salt water intrusion along this estuary due to extensive sand mining has increased over the years. Thus, the focus of the current research is to understand the relationship between river sand mining, salt water intrusion, and the resultant effects on construction sand. Two surveys were conducted along the Kaluganga Estuary along an 11 km stretch from the river mouth at predetermined intervals to measure depth water quality profiles, and to collect sediment samples. These surveys were carried out during maximum spring tide; first in a dry period and then in a wet period, to understand hydrographic effects on the quality of river sands. Sand samples were analysed for absolute chloride content and grain size distribution. Results showed significant salt water intrusion during the dry period, averaging 2,307 μS cm^?1 in surface waters throughout the surveyed 11 km stretch along with 3,818 μS cm^?1 (average) in bottom waters up to 5.6 km upstream from the river mouth causing above normal chloride content in the bottom sandy sediments. The high chloride content in bottom sands was recorded up to 5.5 km from the river mouth making them unsuitable for construction purposes. However, during wet period, salt water intrusion levels in the bottom waters were insignificant (average 61 μS cm^?1) and the chloride content in bottom sediments was very low. This study highlighted the requirement for regulations on river estuary sandmining for construction purposes.     

北京怀柔地区入渗河水空间分布研究

河水入渗路径和范围对确定地下水补给条件,以及水资源调控和合理利用有着重要意义。针对2015年以来怀柔地区地下水水位回升现象,开展了地下水动态影响因素研究,采集了河水和地下水样品,测试了水化学和氢氧稳定同位素组成。δD-δ18 O数据表明该区有河水入渗补给地下水,河流附近地下水为地下水与入渗河水的混合物。利用地下水δ18O值以及二元混合模型计算了地下水中入渗河水的比例,揭示出地下水中河水占比减小方向与地下水水力梯度下降方向一致;局部河段附近地下水Cl-含量增加,表明河水入渗会引起地下水水质变化。入渗河水影响范围的圈定为评价入渗河水对地下水的影响提供了重要数据。该项工作对理解研究区地下水水文过程、控制因素以及水资源管理具有指导意义。     

A Comparison of Water Quality Between Low- and High-Flow River Conditions in a Tropical Estuary, Hilo Bay, Hawaii

Effects of storms on the water quality of Hilo Bay, Hawaii, were examined by sampling surface waters at 6 stations 10 times during low-flow and 18 times during high-flow (storms) river conditions. The direction of a storm’s impact on water quality parameters was consistent among storms and most stations; however, direction of the impact varied with the parameter. High river flow conditions increased concentrations of nitrate and decreased those of dissolved organic nitrogen (N); effects on ammonium and particulate N were station specific. Storms also increased dissolved organic and particulate carbon (C) concentrations. Dissolved phosphorus (P) concentrations were not affected by high river flow events. Dissolved organic forms dominated the N, C, and P pools under both low- and high-flow river conditions. Soil-derived particles and fecal indicator bacteria increased during storms, while chlorophyll a concentrations and bacterial cell abundances decreased. Our results suggest that an increase in storms with global warming could impact water quality of tropical estuaries.     

Evaluation of spatial and seasonal variations in surface water quality using multivariate statistical techniques

In this study, spatial and seasonal variations of water quality in Haraz River Basin were evaluated using multivariate statistical techniques, such as cluster analysis, principal component analysis and factor analysis. Water quality data collected from 8 sampling stations in river during 4 seasons (Summer and Autumn of 2007, Winter and Spring of 2008) were analyzed for 10 parameters (dissolved oxygen, Fecal Coliform, pH, water temperature, biochemical oxygen demand, nitrate, total phosphate, turbidity, total solid and discharge). Cluster analysis grouped eight sampling stations into three clusters of similar water quality features and thereupon the whole river basin may be categorized into three zones, i.e. low, moderate and high pollution. The principle component analysis/factor analysis assisted to extract and recognize the factors or origins responsible for water quality variations in four seasons of the year. The natural parameters (temperature and discharge), the inorganic parameter (total solid) and the organic nutrients (nitrate) were the most significant parameters contributing to water quality variations for all seasons. Result of principal component analysis and factor analysis evinced that, a parameter that can be significant in contribution to water quality variations in river for one season, may less or not be significant for another one.     

Biogeochemistry of the Madeira river basin

A biogeochemical characterization of the Madeira river basin has been made to evaluate the local and global effects of possible alterations in the ecosystem caused by recent intensive occupation in Rondonia state. During the period April 1983—January 1986, sampling was made both by land and river along the tributaries and main channel of the Madeira river. The parameters analysed lead to a detailed study of the physicochemical quality of the waters of the basin and their relationship with the local geology, associated with the transport of solid material and the hydrological behavior of the ecosystem.Penman's method adapted to tropical rainforest conditions was used to evaluate the potential evapotranspiration for the basin. Estimated potential evapotranspiration was 1420 mm/y, 77% due to the energy balance. Real evapotranspiration was 94% of the estimated potential and the main residence time of the rain water in the basin was 2 months. The isotopic behavior of Hydrogen and Oxygen in the river waters of the region was typical of great rivers, the values being more positive during the dry season and more negative during the rainy season. An isotopic gradient of ¹⁸O 0.038 ()/100 km, was established from Porto Velho station to the estuary, which was considered low when compared with the value of 0.063 ()/100 km, obtained for the Amazon river.In general, the waters of the tributaries were poor in dissolved ion species when compared with the main channel of the Madeira river. Seasonal variation in the transport of suspended sediment kept the same pattern, greater transport being observed on rising water than during high water. A transport of 2.85 million tons per day was observed in the Madeira river near the mouth.     

Phytoplankton Biomass and Composition in a River-Dominated Estuary During Two Summers of Contrasting River Discharge

Estuaries located in the northern Gulf of Mexico are expected to experience reduced river discharge due to increasing demand for freshwater and predicted periods of declining precipitation. Changes in freshwater and nutrient input might impact estuarine higher trophic level productivity through changes in phytoplankton quantity and quality. Phytoplankton biomass and composition were examined in Apalachicola Bay, Florida during two summers of contrasting river discharge. The <20 μm autotrophs were the main component (92?±?3 %; n?=?14) of phytoplankton biomass in lower (<25 psu) salinity waters. In these lower salinity waters containing higher dissolved inorganic nutrients, phycocyanin containing cyanobacteria made the greatest contribution to phytoplankton biomass (69?±?3 %; n?=?14) followed by <20 μm eukaryotes (19?±?1 %; n?=?14), and phycoerythrin containing cyanobacteria (4?±?1 %; n?=?14). In waters with salinity from 25 to 35 psu that were located within or in close proximity to the estuary, >20 μm diatoms were an increasingly (20 to 70 %) larger component of phytoplankton biomass. Lower summer river discharges that lead to an areal contraction of lower (5–25 psu) salinity waters composed of higher phytoplankton biomass dominated by small (<20 μm) autotrophs will lead to a concomitant areal expansion of higher (>25 psu) salinity waters composed of relatively lower phytoplankton biomass and a higher percent contribution by >20 μm diatoms. A reduction in summer river discharge that leads to such a change in quantity and quality of estuarine phytoplankton available will result in a reduction in estuarine zooplankton productivity and possibly the productivity of higher trophic levels.     

Dissolved load of the Loire River: chemical and isotopic characterization

The Loire River, with one of the largest watersheds in France, has been monitored just outside the city of Orleans since 1994. Physico-chemical parameters and major and trace elements were measured between 2-day and 1-week intervals according to the river flow. The sampling site represents 34% of the total Loire watershed with 76% silicate rocks and 24% carbonate rocks.

Elements are transported mainly in the dissolved phase with the ratio of total dissolved salts (TDS) to suspended matter (SM) ranging between 1.6 and 17.4. Chemical weathering of rocks and soils are thus the dominant mechanisms in the Loire waters composition. The highest TDS/SM ratios are due to dissolved anthropogenic inputs. The database shows no link between NO₃⁻ content and river flow. The Na⁺, K⁺, Mg²⁺, SO₄²⁻, and Cl⁻ concentrations are seen to decrease with increasing discharge, in agreement with a mixing process involving at least two components: the first component (during low flow) is concentrated and may be related with input from the groundwater and sewage station water, the second component (during high flow) is more dilute and is in agreement with bedrock weathering and rainwater inputs. A geochemical behaviour pattern is also observed for HCO₃⁻ and Ca²⁺ species, their concentrations increase with increasing discharge up to 300 m³/s, after which, they decrease with increasing discharge. The Sr isotopic composition of the dissolved load is controlled by at least five components — a series of natural components represented by (a) waters draining the silicate and carbonate bedrock, (b) groundwater, and (c) rainwaters, and two kinds of anthropogenic components.

The aim of this study is to describe the mixing model in order to estimate the contribution of each component. Finally, specific export rates in the upper Loire watershed were evaluated close to 12 t year⁻¹ km⁻² for the silicate rate and 47 t year⁻¹ km⁻² for the carbonate rate.     

1990-2016年湘江干流水质变化特征及影响因素分析

基于1990-2016年湘江干流主要断面的水质监测数据,采用综合污染指数法、Spearman秩相关检验和主成分分析法对流域水环境质量演变特征进行综合评价,并结合社会经济指标识别流域主要污染源。综合污染指数结果表明湘江水环境变化趋势明显分为两个阶段,1990-1996年间为水质变好阶段,除个别值外污染指数均小于0.2,1997-2016年间水质呈恶化趋势,水质维持在Ⅲ~IV类之间;Spearman秩相关检验结果表明污染物浓度总体呈增加趋势,其中TP、COD_Mn、Cd、Pb和石油类显著上升;主成分分析结果表明流域污染物主要为NH₄⁺-N、TP和Cd,污染源为生活点源和农业面源,从上游到下游污染程度明显增大,其中湘潭断面水质污染最严重,综合得分为0.9006,道县断面相对较轻,综合得分为-0.7014,城镇化因素是影响流域水环境的主要驱动因素。研究结果可为流域水环境保护和水生态修复提供科学依据。     

Geochemistry of trace elements in surface waters of the Arno River Basin,northern Tuscany,Italy

Trace element geochemistry of the Arno River and its main tributaries was investigated on the basis of two sampling campaigns carried out in November 1996 and June 1997. By analyzing filtered and unfiltered water samples, Fe and Al are found in solution mainly as colloidal particles of size lower than 0.45 μm. In June (lower flow rate), Fe and Al are enriched in the filtered waters from the main river, and this feature was interpreted in terms of higher water temperature promoting the formation of smaller particles, thus reducing their aggregation properties. Iron and Al show perfectly synchronous downstream profiles along the Arno River, correlate quite well each to other, and display abrupt concentration increases near to Florence, where the lithology of the catchment changes from siliciclastic dominated to clay-sand (lacustrine-marine)-dominated. The same behaviour is shown by most of the other trace elements in the river, thus supporting a general lithological control. Trace elements in the final part of the Arno River are influenced by flocculation processes in addition to mixing. Adsorption phenomena on oxy-hydroxides are denoted by good elemental correlations with Fe (and Al). Sporadic anomalous concentration values, possibly related to anthropogenic contributions, may prevent such correlations. Referring to the quality of waters for potable use and fish life, toxic elements are below the acceptable limits of current European regulations, with few exceptions for Hg exceeding guideline values. Multivariate analysis groups trace elements according to geochemical affinities and natural or anthropogenic sources, thus distinguishing contaminated from uncontaminated samples. The results achieved in this work will help regional and national Authorities for compliance with the EU water policy, especially in assessing the water quality at the river basin scale and its vulnerability to human activities.     

Assessment of seasonal variations of chemical characteristics in surface water using multivariate statistical methods

Water pollution has become a growing threat to human society and natural ecosystems in the recent decades. Assessment of seasonal changes in water quality is important for evaluating temporal variations of river pollution. In this study, seasonal variations of chemical characteristics of surface water for the Chehelchay watershed in northeast of Iran was investigated. Various multivariate statistical techniques, including multivariate analysis of variance, discriminant analysis, principal component analysis and factor analysis were applied to analyze river water quality data set containing 12 parameters recorded during 13 years within 1995–2008. The results showed that river water quality has significant seasonal changes. Discriminant analysis identified most important parameters contributing to seasonal variations of river water quality. The analysis rendered a dramatic data reduction using only five parameters: electrical conductivity, chloride, bicarbonate, sulfate and hardness, which correctly assigned 70.2 % of the observations to their respective seasonal groups. Principal component analysis / factor analysis assisted to recognize the factors or origins responsible for seasonal water quality variations. It was determined that in each season more than 80 % of the total variance is explained by three latent factors standing for salinity, weathering-related processes and alkalinity, respectively. Generally, the analysis of water quality data revealed that the Chehelchay River water chemistry is strongly affected by rock water interaction, hydrologic processes and anthropogenic activities. This study demonstrates the usefulness of multivariate statistical approaches for analysis and interpretation of water quality data, identification of pollution sources and understanding of temporal variations in water quality for effective river water quality management.     

Application of multivariate statistical techniques in the assessment of water quality in Sakarya River,Turkey

In this paper, the surface water quality of the Sakarya River in Turkey is assessed by using multivariate statistical techniques. These techniques were applied to the chemical parameters obtained from the five different surface water quality observation stations. Factor and principal component analysis results reveal that the agricultural, anthropogenic and domestic pollution caused differences in terms of water quality. Cluster analysis revealed two different clusters of similarities between the stations, reflecting different chemical properties and pollution levels in the studied river. Surface water quality downstream of the river was different from the water quality upstream. Thus, this study shows the usefulness of multivariate statistical techniques for analysis and interpretation in the surface water quality problem.     

Coastal water pollution in two rivers of the Bengal delta

A thorough comprehension of relevant environmental parameters is a prerequisite to preventing coastal degradation and environmental balance in coastal zones. In this study, we correlate major physicochemical of two coastal rivers (Matla and Saptamukhi) in the Sunderban district, West Bengal. The parameters namely: pH, salinity, dissolved oxygen, suspended solids, nitrogen and phosphorus concentrations (inorganic and total) of these two rivers were studied in detail over the 90s decade. We hypothesized that both natural and anthropogenic activities during that time have contributed to the pollution and employed the above parameters to test our hypothesis. Our results reveal that the quality of waters in the rivers have been showed to be dependent on flood impacts, storm surge, eutrophication, domestic sewage, agricultural and industrial wastes. Thus, both natural and anthropogenic causes are the behind coastal pollution of river waters. We conclude that they have all contributed to pollution of these rivers in various ways and we calculate the differential effects of these parameters on coastal pollution.     

水质站网规划研究中几个问题的探讨

在进行中国水质站网规划布设合理的性研究中，按河流水系将全国国土分为若干水质站网规划单元分区，然后运用主成分聚类方法进行单元分区类型的划分，作为水质站网规划的基础。在同一类型单元分区内，运用模糊集合聚类方法，将分区内的水质进行分类，以确定水质站的布设密度，并对每一水质参数的采亲频次进行分析研究，以指导确定其采样频次。