scholarly journals Study of Water and Sediment Quality in the Bay of Dakhla, Morocco: Physico-Chemical Quality and Metallic Contamination

2020 ◽  
Author(s):  
Mimouna Anhichem ◽  
Samir Benbrahim

The present study contributes to the evaluation of the impact of the various activities developed around the Bay of Dakhla in Morocco through the study of the physico-chemical quality of the waters and sediments of the Bay. For this purpose, a spatial and temporal monitoring of the physicochemical and metallic pollution indicator parameters was conducted between May 2014 and March 2015. The main physicochemical descriptors of water quality were monitored, namely: temperature, salinity, pH, dissolved O2, nutrients (ammonium, nitrites, nitrates, phosphates) and chlorophyll (a). A qualification of the waters of the Bay was drawn up based on water quality assessment grids. The quality of the sediments was assessed through the determination of granulometry, the total organic carbon content and the contents of the main metallic trace elements (cadmium, lead, mercury, chromium, copper and zinc). The results of the present study show the beginning of nutrient enrichment of the water bodies of the bay, especially the stations located near the urban area, where 1.83 mg l−1 of nitrates, 0.37 mg l−1 of phosphate and 7.42 μg l−1 of chlorophyll (a) were recorded. For the sediment, the maximum concentrations of metallic trace elements were recorded in the station near the harbour basin. These results allowed to establish a quality grid for the waters of the bay, generally qualified as “Good”, except for the sites located near the urban area for which the quality is qualified as “Average”. The sediment quality of the bay was assessed according to the criteria established by the Canadian Council of Ministers of the Environment. The levels of metallic trace elements remain below the toxicity thresholds, except for the sediments taken from the harbour basin.

2017 ◽  
Vol 9 (2) ◽  
pp. 188-195
Author(s):  
Oluwafisayo A. YUSUF ◽  
Henry A. ADEWOLE ◽  
Victor F. OLALEYE

The water quality and concentrations of selected heavy metals (cadmium, lead, and zinc) in Saba River, Osogbo were assessed monthly over a period of six months with a view to providing information on the water quality of the potentially polluted urban river system. Three sampling sites were selected along the Saba River (the upper reach of the river (Station A), mid-point of the river (Station B) and the lower reach of the river where it emptied into River Osun (Station C)). The recorded ambient air and water temperature, pH, alkalinity conductivity, total hardness, BOD and COD, as well as the phosphate and nitrate levels of Saba River, were within the maximum allowable regulatory limits of WHO (2011). The dissolved oxygen level between March and April in all the sampling points were in the limit of putting aquatic life under stress (<5.0 mg/L). Also the alkalinity level in station B between February and June, and in Station C from February till May were however above the maximum allowable desirable range of EPA (2001) and WHO (2011). The concentration of zinc, which ranged from 717 to 1,000 µg/L, was the highest amongst the selected metals assayed in the water. However, the mean concentration of lead in the water samples collected from Stations B and C (26 µg/L and 24 µg/L, respectively) was found to be above recommended regulatory acceptable limits of 20 µg/L of WHO (2011) and FEPA (2007). The study concluded that the physico-chemical indices of the water quality indicated that the river was mildly polluted.


2019 ◽  
Vol 19 (7) ◽  
pp. 2021-2027 ◽  
Author(s):  
María Micaela Ledesma ◽  
Matías Bonansea ◽  
Claudia Rosa Ledesma ◽  
Claudia Rodríguez ◽  
Joel Carreño ◽  
...  

Abstract The physico-chemical and biological composition of a reservoir's effluents directly influences water quality. The values of variables such as high values of concentrations of chlorophyll-a (Chl-a) are indicators of pollution. The objective of this work was to monitor the trophic status and water quality of the Cassaffousth reservoir (Córdoba, Argentina) through the development of statistical models based on field data and satellite information. During 2016 and 2017, samples were taken bimonthly. Seven sampling sites were selected and physico-chemical and biological parameters were assessed. By using regression techniques, Landsat 8 information was related with field data to construct and validate a statistical model to determine the distribution of Chl-a in the reservoir (R2 = 0.87). The generated algorithm was used to generate maps which contained information about the dynamics of Chl-a in the entire reservoir. Remote sensing techniques can be used to expand the knowledge of the dynamics of the Cassaffousth reservoir. Moreover, these techniques can be used as baselines for the development of an early warning system for this and other reservoirs in the region.


2019 ◽  
Vol 21 (2) ◽  
pp. 437-453
Author(s):  
Elna Lucilia Santos Corrêa ◽  
Karina Suzana Feitosa Pinheiro ◽  
Cláudio José Da Silva de Sousa ◽  
Luiz Jorge Bezerra da Silva Dias

O Brasil apresenta grande disponibilidade de água doce em seus mananciais. Fazendo parte desse recurso encontra-se, o rio Paciência, localizado na Ilha do Maranhão destacado pela sua importância local, principalmente por contribuir com suas águas para recarga dos mananciais subterrâneos, fonte de abastecimento público de vários bairros de São Luís, capital do estado. No entanto, este rio vem sofrendo comprometimento da qualidade de suas águas, consequência do processo de uso e ocupação dos espaços em sua bacia. Destacando-se como um dos principais problemas relacionados a qualidade de ambientes fluviais,  a eutrofização, que consiste no processo em que o corpo d’água adquire elevados níveis de nutrientes (fosfatos e nitratos), é um indicador determinante da qualidade da água. Neste sentido, o objetivo deste trabalho foi caracterizar a qualidade da água e do estado trófico na bacia hidrográfica do rio Paciência atráves dos parâmetros fisico-químico evidenciando os trechos mais comprometidos conforme os valores alcançados nas análises. Os resultados das análises foram comparados com a CONAMA No. 357/05 que indicaram uma situação preocupante quanto à qualidade da água no local de estudo.Palavras-chave: Qualidade de água; Eutrofização; Ilha do Maranhão. ABSTRACTThe Brazil has great availability of fresh water in its springs. Within these contexts, the Paciência River, located on the Island of Maranhão stands out for its local importance, mainly for contributing its waters to the recharge of the underground springs, source of public supply of several districts of São Luís, capital of the state. However, this river has been compromising the quality of its waters, a consequence of the process of use and occupation of the spaces in its basin. Highlighting as one of the main problems related to the quality of fluvial environments, eutrophication, which consists of the process in which the body of water acquires high levels of nutrients (phosphates and nitrates), is a determinant indicator of water quality. In this sense, the objective of this work was to characterize the water quality and trophic status in the Paciência river basin through the physico-chemical parameters, showing the most compromised stretches according to the values reached in the analyzes. The results of the analyzes were compared with CONAMA No. 357/05 which indicated a worrying situation regarding the quality of the water at the place of study.Keywords: Water quality; Eutrophication; Island of Maranhão. RESUMENBrasil tiene gran disponibilidad de agua dulce en sus manantiales. Parte de este recurso es el río Paciencia, ubicado en la isla de Maranhão, que destaca por su importancia local, principalmente porque contribuye con sus aguas a recargar las fuentes subterráneas, fuente de suministro público de varios barrios de São Luís, capital del estado. Sin embargo, este río se ha visto afectado por la calidad de sus aguas, como consecuencia del proceso de uso y ocupación de los espacios en su cuenca. Destacando como uno de los principales problemas relacionados con la calidad de los ambientes fluviales, la eutrofización, que consiste en el proceso en el que el cuerpo de agua adquiere altos niveles de nutrientes (fosfatos y nitratos), es un indicador determinante de la calidad del agua. En este sentido, el objetivo de este trabajo fue caracterizar la calidad del agua y el estado trófico en la cuenca del río Paciência a través de los parámetros fisicoquímicos, mostrando las secciones más comprometidas de acuerdo con los valores alcanzados en los análisis. Los resultados de los análisis se compararon con CONAMA N°. 357/05, que indicó una situación preocupante con respecto a la calidad del agua en el sitio de estudio.Palabras clave: Calidad del agua; Eutrofización, Isla Maranhão.


1993 ◽  
Vol 27 (5-6) ◽  
pp. 61-67 ◽  
Author(s):  
E. Jacobs ◽  
J. W. van Sluis

The surface water system of Amsterdam is very complicated. Of two characteristic types of water systems the influences on water and sediment quality are investigated. The importance of the sewer output to the total loads is different for both water systems. In a polder the load from the sewers is much more important than in the canal basin. Measures to reduce the emission from the sewers are much more effective in a polder. The effect of these measures on sediment quality is more than the effect on water quality. Some differences between a combined sewer system and a separate sewer system can be found in sediment quality.


2011 ◽  
Vol 17 (1) ◽  
pp. 107-115 ◽  
Author(s):  
Nada Babovic ◽  
Dejan Markovic ◽  
Vojkan Dimitrijevic ◽  
Dragan Markovic

This paper shows the results obtained in field analysis performed at the Tamis River, starting from the settlement Jasa Tomic - border between Serbia and Romania to Pancevo - confluence of Tamis into the Danube. The Tamis is a 359 km long river rising in the southern Carpathian Mountains. It flows through the Banat region and flows into the Danube near Pancevo. During the years the water quality of the river has severely deteriorated and badly affected the environment and the river ecosystem. In situ measurements enabled determination of physico-chemical parameters of water quality of the Tamis River on every 400 m of the watercourse, such as: water temperature, pH value, electrical conductivity, contents of dissolved oxygen and oxygen saturation. The main reason of higher pollution of Tamis is seen in connection to DTD hydro system. Sampling was performed at 7 points with regard to color, turbidity, total hardness, alkalinity, concentration of ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, iron, chlorides and sulphates in samples. The aim of the present work was to evaluate water quality in the Tamis River taking into account significant pollution, which originates from settlements, industry and agriculture, and to suggest appropriate preventive measures to further pollution decreasing of the river's water.


2014 ◽  
Vol 11 (1) ◽  
pp. 31-48 ◽  
Author(s):  
Katharina Kern

Directive 2013/39/EU amending Directives 2000/60/EC and 2008/105/EC as regards priority substances in the field of water policy was adopted on 12 August 2013. It revises crucial rules on determining the chemical quality of surface water in Europe (e.g. identification of new harmful substances, updating of environmental quality standards, introduction of a new “watch list” mechanism) and establishes new standards for the protection of water in Europe. This paper explores the legal and factual background to the new legislation on protecting water quality in Europe and takes a critical look at its most important provisions.


Author(s):  
Leonardo Brandão Nogueira ◽  
Sabriny Melo Sousa ◽  
Camila Gonçalves Lobo Santos ◽  
Gustavo Simões Araújo ◽  
Laser Oliveira ◽  
...  

Mining waste is rich in trace elements, which present a high toxic potential and may represent a risk for aquatic ecosystems. The Fundão dam failure, considered the largest environmental disaster in the world, affected 663.2 km of watercourses, including Carmo and Gualaxo do Norte Rivers. The ore tail also affected the riverside communities, destroying villages, killing people and affecting the subsistence farming. To evaluate the influence of the mine tailing wave on the water quality of the Carmo and Gualaxo do Norte Rivers water samples were collected at nine points located in Barra Longa during the rainy season. Physicochemical parameters (conductivity, resistivity, EH, total dissolved solids, pH and temperature) and major, minor and trace elements concentrations (Ba, Co, Cr, Cu, Ni, Sc, Sr, V, Zn, As, Pb, Al, Fe, Mn, Ca, K, Mg and P) were evaluated and compared with previous studies and conformity limits established by a national resolution (CONAMA Resolution N°357/2005). Only conductivity, Fe and Mn presented non-conformity values according to CONAMA Resolution N°357/2005. These results may be related not only to the dam burst but also to the rainy season and non-detectable pollution sources. Furthermore, the decreased levels in the toxic elements in the rivers over time, may be related to its association with sediments in addition to their flux to the Atlantic Ocean. Thus, after nearly six years, the environmental and social impacts are still alive and the minerals dragged to the riverbed could bring cumulative effects for the entire environment what means an uncertain future to the Rio Doce Basin and adjacent coastal zone.


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