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This study presents the first data on levels of natural radioactive elements in sediments from coastal ecosystems of the Republic of Congo. Sediment samples from five coastal sites were collected and analyzed by high-resolution gamma spectrometry for determination of activities of long-lived gamma-emitting radionuclides (234Th, 238U, 226Ra, 210Pb, 228Th, 228Ra, and 40 K). The specific activities were of the same order of magnitude as those measured in sediments of most countries neighboring the Republic of Congo. However, variations in activities were observed from one site to another and also from one sampling point to another within the same site without exceeding the global average reference values. It can be assumed, therefore, that no significant anthropogenic impact is perceptible in the study area. The most commonly used radiological hazard parameters, based mainly on 238U, 232Th, and 40 K activities, were assessed and the ERICA tool was applied to quantify the radiation exposure burden to human and biota resulting from radionuclides in sediments. Besides being useful for future monitoring efforts, the data produced in this work could be important for the worldwide database on radioactivity in the oceans and seas (MARIS) since no data are available in the Congolese marine environment. [ABSTRACT FROM AUTHOR]

The present work assesses the temporal distribution pattern and geochemical changes of rare earth elements and Yttrium, Scandium, Thorium, and Uranium delivery into the Oualidia lagoon. Two sediment cores were retrieved from the Oualidia lagoon and analyzed using neutron activation analysis. The results indicated that heavy rare earth elements are slightly enriched the sediment cores over light rare earth elements. The highest values of REEs were recorded in the top layers of the cores and depleted with depth, suggesting a possible change in factors controlling their accumulation, including mechanical, chemical, and environmental parameters such as weathering intensity, grain size, and Fe-Mn oxides. The sediments display positive Ce anomalies, which are probably related to the submarine weathering process and detrital input. Noting also the variation of hydrodynamics conditions and confinement of the upstream part of the lagoon played a key role in changing the sediment origins. Thus, further investigation of REEs origin in the Oualidia lagoon sediment is required to identify their sources, provenances, and the factors controlling their spatial and vertical distributions. However, these results provide baseline data of occurring changes in REEs geochemical composition and constitute a typical study case to understand the link between sedimentary and geochemistry processes in a lagoonal ecosystem. [ABSTRACT FROM AUTHOR]

Plastic pollution presents a major challenge facing stakeholders and decision-making worldwide. Plastics in the ocean damage biodiversity and marine ecosystem services that the blue economy relies upon. The present work analyses and reviews the literature on plastic pollution and the background knowledge about marine plastic pollution in Morocco. The economy of Morocco depends mainly on marine activities, including fisheries, tourism, and maritime trade. These sectors were identified as the main in-situ sources of plastics entering Moroccan coastal waters. The analysis results showed that the increasing abundance of plastics in such marine systems causes substantial economic loss to blue economy activities. In contrast, the lack of data on the plastic waste quantity entering Moroccan water is a limiting factor for assessing plastic pollution. This highlights the need for a risk assessment and more field investigations to value the weight impacts of marine activities generators of plastics on biodiversity and the economy. In addition, implementing laws and rules forbidding the disposal of plastic waste (PW) in public spaces, mainly beaches, and streets, is urgently needed. Raising awareness of plastic waste management and prioritizing improved waste collection, sorting, and management would boost Morocco's establishment and adoption of circular economy strategies. It is worth noting that while implementing the management projects and regulatory frameworks of plastic waste, considering their source and usage purpose is mandatory. [ABSTRACT FROM AUTHOR]

In this study, gross alpha and gross beta activities in 14 bottled mineral waters in Morocco were measured by Liquid Scintillation Counting following the standard method ISO 11704:2018. Method verification was carried out using standard approaches to confirm the performance parameters of the method, being used routinely in our laboratory. Gross alpha and gross beta activities lie between minimum < DL (below detection limit) and maximum 0.211 ± 0.015 and 0.151 ± 0.008 Bq L− 1 respectively. No significant correlation was found between activities and total dissolved salts (TDS) contents, ranging from 141 to 2078 mg L− 1. [ABSTRACT FROM AUTHOR]

210Po, 210Pb, and 137Cs activities were measured using gamma and alpha spectrometry in commonly consumed seafood collected from the local fish market of Kenitra, Morocco. 210Po activity ranged from 0.76 to 182.5 Bq kg−1 w.w, while 210Pb and 137Cs activities were 1 and 4 Bq kg−1 w.w, respectively. The potential health risks associated with the consumption of seafood were assessed through the calculation of the committed effective dose, the daily intake, and the lifetime cancer risk. The obtained results of the committed effective dose were below the limit (1 mSv year−1), while the lifetime cancer risk exceeded the range of acceptable values. [ABSTRACT FROM AUTHOR]

The present study evaluates the distribution of metals over the last 100 years in the Oualidia lagoon by examining their concentrations in the sediment cores. The samples were analyzed by instrumental neutron activation analysis and inductively coupled plasma mass spectrometry. Activities of 210Pb, 226Ra, and 137Cs were determined by gamma-ray spectrometry for establishing the age-depth relationships throughout the sediment cores by applying conventional models. The results indicated that the study area is contaminated by As and Cd revealing a detectable anthropogenic input of occurring metals as a consequence of the continuous development of human activities around the lagoon since 1950. The enrichment factor calculated for each layer of the three cores revealed that the studied sediments present no enrichment by Pb, K, and Mn; minor enrichment by Zn, Cr, Co, Cu, V, and Ni; and a moderately to severe enrichment by As and Cd. The pollution load index values increase from the bottom to the top of cores, and ranged from 0.9 to 2.8, which indicates levels of pollutants ranging from background to relatively high concentrations in the investigated sediments. [ABSTRACT FROM AUTHOR]

Naturally occurring radionuclides and Cs were measured in a sediment core and surface deposit collected from the bed channel of the Oualidia Lagoon located in the western Morocco. Major and rare earth elements (REE) profiles were determined by instrumental NAA technique. Pb and Cs were used to establish the sedimentation chronology over the last decades by using conventional models. Pb displayed relatively higher concentrations and rate of supply to the sediment than typical levels found in other coastal areas in Morocco. REE ratios and Ce anomalies showed that the direct incorporation of particles from seawater to the bed sediment is the most important, followed by the terrigenous component. [ABSTRACT FROM AUTHOR]

This study presents metal concentrations (Fe, Mg, Mn, Co, Cu, Zn, Pb, As, Sr and V) and radionuclide activities (K, Cs, Pb, Ra, Ac, Th and Pb) in surface deposits and a sediment core from the Sebou Estuary, Northwest Morocco. Samples were collected in April 2009, about 2 months after a flooding event, and analysed using a well-type coaxial gamma-ray detector and inductively coupled plasma-quadrupole mass spectrometry. Activities of radionuclides and concentrations of almost all elements in surface samples displayed only moderate spatial variation, suggesting homogenous deposition of eroded local soil in response to intense precipitation. Excess Pb displayed relatively constant activity throughout the sediment core, preventing dating and precluding determination of the historical accumulation rates of pollutants at the core site. Some elements showed non-systematic trends with depth and displayed local maxima and minima. Other elements presented relatively systematic concentration trends or relatively constant levels with discrete maxima and/or minima. Except for Mn, Sr and Cr, all metal concentrations in sediment were below levels typical of polluted systems, suggesting little human impact or losses of metals from sediment particles. [ABSTRACT FROM AUTHOR]

In forensic contexts, time since death assessment in human skeletal remains is crucial for identification, and both accuracy and reliability are required. In this paper, we present the possibilities and constraints of the use of Pb in dating skeletonized human bones in Morocco. The method was tested on recent as well as archaeological bones of known dates of death. A calibration curve was obtained from the available data in the scientific literature. The Pb initial activity was introduced as an increasing lineal function with time. The Pb dating approach gives promising results only for recent bones. On the contrary, for archaeological bones, the technique has erroneously led to post-mortem intervals in the range of recent bones which constitute a serious limitation of the method. On the other hand, uranium isotopes content in bones is suggested in this work as a possible indicator in placing a studied bone within either a forensic or archaeological context. [ABSTRACT FROM AUTHOR]

The one-dimensional path decomposition expression for the step potential and mass is formulated. The propagator is analytically determined and the limiting case m1; m2 → m is exactly obtained. [ABSTRACT FROM AUTHOR]

In estuarine environments there are important spatial and temporal changes in both salt and suspended load concentrations. An experimental procedure have been developed to produce kinetic parameters being representative of the natural environment studied, and we have investigated the effect of salinity and suspended load concentration to the kinetics of the uptake. These results are encouraged by recent advances in environmental modelling concerning to radionuclide dispersion in aquatic natural systems and involving non-equilibrium processes. Experiments are carried out with unfiltered water samples from the Odiel estuary (Southwest of Spain), with133Ba tracer to illustrate experimental procedures. [ABSTRACT FROM AUTHOR]

An improved and rapid method is described for the determination of 90Sr in environmental samples, through the separation of the daughter 90Y at equilibrium. The procedure is based on the HDEHP solvent extraction in combination with liquid scintillation spectrometry (LSS). A low background QuantulusÔ has been optimized for low level counting of Cerenkov radiation emitted by the hard b-emitter 90Y. The counting efficiency was 60% and the background 0.53 cpm. The reliability and reproducibility of the method have been checked using IAEA reference materials. The chemical recovery for 90Y extraction ranges from 83 to 90%. [ABSTRACT FROM AUTHOR]

Two sediment cores were collected from the Oualidia lagoon, on the Atlantic coast of Morocco, and analyzed for 210Pb and 137Cs activity by gamma spectrometry. The 210Pb profiles were characterized by high activity at specific depths in each core, which were attributed to substantial increases in atmospheric 210Pb input to the sediment. A modified CRS model was applied to develop age-depth relations (chronologies) for the cores and calculate sediment accumulation rates, taking into account changing unsupported 210Pb delivery and specifying the year when the increase began. Calculated 210Pb inventories (activity/area) and fluxes (activity/area/time) depend strongly on sedimentation rates and were much higher than mean values in similar coastal systems worldwide. We attempted to use 137Cs as a time marker to support the modified CRS chronologies for both cores. The 137Cs profiles, however, were affected by post-depositional cesium migration in the sediment which made it difficult to identify the 1963 atmospheric bomb-testing peak, especially in the core with low sedimentation rate. We conclude that the high activities of 210Pb detected at specific depths in the Oualidia lagoon sediment cores are a consequence of decay of radioactive 222Rn, which displayed periodic high concentrations in the overlying atmosphere. [ABSTRACT FROM AUTHOR]