The seasonal and spatial variations of particulate matter (PM2.5-10 and PM2.5) and its chemical composition have been studied over a one-year period in Kenitra city (2007-2008). The samples were ...collected using Gent stacked filters and dichotomous samplers in two size fractions: below 2.5 μm (fine) and 2.5 to 10 μm (coarse). The chemical compositions of the collected filters were evaluated by using Total X-ray Fluorescence and Atomic Absorption Spectroscopy. The influence of atmospheric transport scenarios on the levels of PM was elaborated by means of air mass back-trajectories, using the HYSPLIT™ model. This study allowed identifying four main transport patterns: short local flows over the Kenitra region, Northwesterly flows over the Atlantic Ocean, Northerly flows, and Southern flows. The highest PM2.5-10 concentrations were observed in the summer and the lowest in the winter. However, no significant seasonal variations were discerned for PM2.5 particles. The enrichment factor and risk assessment code were calculated to distinguish between anthropogenic influences and the natural background levels and assess the environmental risks of metals in PM2.5-10 and PM2.5 particles. A comparison of PM and metal concentrations in Kenitra city and other African cities (reported in the literature) revealed that that the values obtained in Kenitra city are significantly higher than those recorded for the other African cities (that are the subject of the comparison).
At an urban site in Kenitra, Morocco, two aerosol size fractions (PM2.5 and PM10) were sampled for four seasons to characterize the seasonal trends of particulate (PM) and carbonaceous (BC) aerosols. ...An in-depth statistical analysis of the lag-effects of meteorology on collected data was investigated using uni- and multivariate linear regression analyses. The results revealed significant seasonal trends for PM10, PM2.5, and BC. PM concentrations showed the maximum values in autumn (61.4 ± 24.5 µg/m3 for PM10 and 21.2 ± 8.2 µg/m3 for PM2.5), while the minimum was observed in winter (40.2 ± 17.1 µg/m3) for PM10 and in summer (14.3 ± 3.3 µg/m3) for PM2.5. High BC concentrations were recorded in summer (6.3 ± 4.2 μg/m3, on average). The relative humidity 1–2 days earlier showed a higher negative correlation with the PM concentrations (except in winter), and the temperature 1–3 days earlier showed a negative correlation with the PM2.5 in winter and summer and a positive one with the PM10 in autumn. Wind speed was negatively associated with PM10 on the current day in winter and 3 days earlier in summer. However, diverse effects of wind speed on PM2.5 were observed (negative in summer and positive in spring). These results confirm the important role of meteorology in the formation of urban air pollution with pronounced variations in different seasons.
Insufficient data on the chemical composition of PM2.5 and its emission sources in the southwestern (SW) Mediterranean area has been identified. Ambient PM2.5 samples were collected in an urban area ...of Tetouan city, northern Morocco. Chemical mass closure calculations and positive matrix factorization were performed for the comprehensive dataset of PM2.5 chemical analyses. Mass closure improved when multipliers (1.2 and 0.23, respectively) were used for the conversion of organic carbon (OC) and calcium ion (Ca2+) into particulate organic matter (POM) and mineral dust masses, respectively. The mass closure model performed well in this SW Mediterranean region, with a significant correlation (r2 = 0.97) obtained between gravimetrically measured and chemically determined PM2.5 mass. The one-year average concentration of PM2.5 was 17.96 μg/m3, and the major chemical components were POM (34%), secondary inorganic aerosol (SIA) (28%), and black carbon (18%), while unidentified mass was 4%. The mass concentration and most of the chemical components of PM2.5 showed clear seasonal variations, with a summer-high and winter-low pattern for SIA, dust, and BC. In the winter months, POM was the dominant component. Source apportionment analysis revealed that PM2.5 emission sources, regarding their typical tracers, were ammonium sulfate (SO42−, NH4+, K+, NO3−), road traffic and biomass burning emissions (OC, BC), fresh sea salt (Cl−, K+, NO3−), aged sea salt (Mg2+, Na+, Ca2+), and oxalate-rich (oxalate, NO3−) factors. Further, it is hoped that these findings help to improve the scientific understanding of SW Mediterranean aerosols.
Marchica Lagoon, a Ramsar site on the Mediterranean coast of Morocco, is experiencing the impacts of watershed pollution, which includes pollutants from the domestic, agricultural, industrial, and ...mining sectors. Restoration actions were undertaken around this lagoon during the last decade in order to protect its ecological value and to develop tourist activity. To conserve the biodiversity in the lagoon, it is important to assess the environmental state of this ecosystem. This study aims to evaluate the ecotoxicological state of sediments through the post restoration characterization of the trace elements Pb, Cu, Zn, Cr, Co, and Ba, as well as their correlation to the major elements, grain size, and total organic carbon, sampled during two campaigns (the wet and dry seasons of 2018) across a sampling network of thirteen stations. Multivariate analysis and ecotoxicological risk assessment of the trace elements using the sediment quality guidelines and five pollution indices (geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (CF), pollution-load index (PLI), and mean effect range median quotient (m-ERM-Q)) revealed contamination of the lagoon by Pb, Zn, and Cu, and minimal pollution by Cr, Co, and Ba. The distribution of the biological-risk index reveals that four zones of the lagoon may present a high probability of toxicity, thus constituting potential risk areas for aquatic organisms: during the wet season, the area in the northwestern sandbar border, the southwest eutrophication zone, and the mouth of the stream valley conveying industrial discharges; and during dry season, the northwestern eutrophication zone. Despite the restoration actions achieved around the lagoon, the lead, zinc, and copper concentrations increased, and their variation was significant between group stations. The biodiversity conservation of Marchica Lagoon requires continuous monitoring and assessment, as well as the implementation of an integrated management plan with restoration actions, not only around the lagoon, but also at its watershed level.
Covid-19 was first reported in Morocco on March 2, 2020. Since then, to prevent its propagation, the Moroccan government declared a state of health emergency. A set of rapid and strict ...countermeasures have taken, including locking down cities, limiting population's mobility and prohibiting almost all avoidable activities. In the present study, we attempted to evaluate the changes in levels of some air pollutants (mainly PM10, NO2 and SO2) in Salé city (North-Western Morocco) during the lockdown measures. In this context, a continuous measurement of PM10, SO2 and NO2 was carried before and during the Covid-19 lockdown period. As a consequence of the security measures and control actions undertaken, the emissions from vehicle exhaust and industrial production were significantly reduced, which contribute to the decrease in the concentrations of the studied pollutants. The obtained results showed that the difference between the concentrations recorded before and during the lockdown period were respectively 75%, 49% and 96% for PM10, SO2 and NO2. PM10 levels were much less reduced than NO2. The three-dimensional air mass backward trajectories, using the HYSPLIT model, demonstrated the benefits of PM10 local emission reductions related to the lockdown were overwhelmed by the contribution of long-range transported aerosols outside areas. In addition, noteworthy differences in the air mass back trajectories and the meteorology between these two periods were evidenced.
Daily average concentrations of SO2 and NO2 from March 11th to April 2nd in Salé city. Display omitted
•PM10, NO2 and SO2 concentrations were reduced by more than half during the covid-19 lockdown period.•Covid-19 countermeasures contribute to reduce all pollutant concentrations but with significant differences among them.•Long-range transported aerosols contributions overcame the PM10 local emission reductions benefits related to the lockdown.
Covid-19 was first reported in Morocco on March 2, 2020. Since then, to prevent its propagation, the Moroccan government declared a state of health emergency. A set of rapid and strict ...countermeasures have taken, including locking down cities, limiting population's mobility and prohibiting almost all avoidable activities. In the present study, we attempted to evaluate the changes in levels of some air pollutants (mainly PM
, NO
and SO
) in Salé city (North-Western Morocco) during the lockdown measures. In this context, a continuous measurement of PM
, SO
and NO
was carried before and during the Covid-19 lockdown period. As a consequence of the security measures and control actions undertaken, the emissions from vehicle exhaust and industrial production were significantly reduced, which contribute to the decrease in the concentrations of the studied pollutants. The obtained results showed that the difference between the concentrations recorded before and during the lockdown period were respectively 75%, 49% and 96% for PM
, SO
and NO
. PM
levels were much less reduced than NO
. The three-dimensional air mass backward trajectories, using the HYSPLIT model, demonstrated the benefits of PM
local emission reductions related to the lockdown were overwhelmed by the contribution of long-range transported aerosols outside areas. In addition, noteworthy differences in the air mass back trajectories and the meteorology between these two periods were evidenced.
Two size fractions of atmospheric particulate matter < 2.5 mu m and 2.5-10 mu m were collected in Kenitra City from February 2007 to February 2008. The sampling was done using a Gent Stacked sampler ...on nuclepore polycarbonate filters and the collected filters were analyzed using Total Reflection X-Ray Fluorescence (TXRF) and Atomic Absorption Spectroscopy (AAS). The particulate matter trends show higher concentrations during the summer as compared to other seasons. The highest concentrations were obtained for Ca in coarse particles and Fe for fine particles. However, the lowest concentrations were observed for Cd in both particulate sizes. The principal component analysis (PCA) based on multivariate study enabled the identification of soil, road dust and traffic emissions as common sources for coarse and fine particles.
This study investigates the sources and characteristics of PM
10
pollution in Tetouan city, Morocco, by employing a combination of chemical mass closure, source-receptor modelling (namely positive ...matrix factorization, PMF), and air mass trajectory statistical analyses (concentration weighted trajectory, CWT). It provides compelling evidence that using such a combination is a powerful approach for studying the composition and sources of PM
10
in the Tetouan region. The PMF analysis identifies four PM
10
sources, namely Vehicle Exhaust, Secondary Aerosols, Nitrate + Biomass Burning, and Fresh Sea Salt, with distinct seasonal contributions. CWT analysis reveals the Mediterranean Basin as the primary source region, with influences from populated areas in northern Morocco, southern Europe, and marine emissions. PM
10
mass closure highlights the abundance of Dust, Particulate Organic Matter (POM), and Water-Soluble Inorganic Ions (WSI), accounting for the majority of the mass. The low OC/EC ratio advocates that carbonaceous aerosols primarily originate from local traffic emissions. Diagnostic of WSI ratios shows that the NH
4
+
/SO
4
2−
ratio indicated an ammonium-poor environment and suggested an acidic nature of the PM
10
aerosols, while the SO
4
2−
/NO
3
−
ratio reflects the combined influence of stationary and mobile sources, with a partial contribution from industrial activities throughout the year. These findings are expected to shed light on the chemical composition, origin of emission sources, and transport pathways of PM
10
in the region, contributing to the understanding of air pollution in the south western Mediterranean.
Although black carbon is one of the most important atmospheric particulate components driving climate change and air quality, there is a lack of comprehensive air quality data from North African ...urban areas. Seven-wavelength aethalometer-collected data were used to provide first insights into the levels and patterns of equivalent black carbon (eBC) mass concentrations, particularly into the seasonal and diurnal cycles, that exist over an urban area in the North of Africa, Kenitra city, Morocco. The average BC mass concentration was observed as 0.90 ± 0.80 μg/m3. This BC value is overall largely lower than reported African and European urban location levels, although the role of COVID-19 restrictions could have influenced this result. The diurnal pattern revealed two BC peaks corresponding to morning and evening traffic rush hours. This variation is found to be seasonally dependent, with the maximum daily amplitude occurring in winter. The BC bimodal behaviour is observed in all the seasons but with varying degrees of the magnitude of the peaks (winter > autumn > summer). This observed seasonal heterogeneity was explained by varying meteorological conditions (wind speed, wind direction, relative humidity, air pressure, air temperature, rainfall, and boundary layer height), and air mass trajectory height and pathways. It was pointed out that the daily and seasonal variations are significantly influenced by local traffic sources, wind speed, and boundary layer dynamics. Hysplit backward trajectories revealed that the long-range aerosols transport through both south-western (Atlantic region), and western (over populated areas) regions can as well contribute to BC concentrations, although to a different extent. Finally, a common thread that runs through seasonal, and diurnal variations were that typical low hourly BC concentrations (distinguished in the afternoon) do not exceed the value of 0.5 μg/m3 representing a kind of urban background level.
Display omitted
•Real-time measurements of black carbon at a North African urban site, Kenitra city.•Low BC levels were observed in Kenitra compared with other African areas.•A well-defined diurnal and significant seasonal variation in BC concentration.•Local traffic activities assumed the major source of BC at the sampling site.•Long-range sources were found to be more prominent during winter.
Nearly 300 million t of phosphogypsum (PG) are produced every year as a byproduct from phosphate fertilizer production worldwide. Approximately 58% of the PG are stacked, 28% are discharged in ...coastal waters and only 14% are further processed. This critical review provides an overview of the physical-chemical properties of PG produced from sedimentary and magmatic phosphate ore worldwide using various analytical tools. Results from more than 25 years of work on PG at École des Mines de Saint-Étienne are presented and critically discussed. In total PG samples from 67 industrial storage sites around the world and PG samples synthesized under different conditions in the laboratory have been considered. The low radioactivity present in PG (particularly PG produced from sedimentary phosphate rock) was identified as the main challenge to using PG as a raw material in construction. Water-soluble and volatile chemical compounds were identified as the main challenge to environmentally sound PG management. Although PG does (in most cases) not pose an immediate threat to the environment the authors recommend processing all PG instead of storing or disposing it, to eliminate potential long-term risks and utilize a relevant secondary resource.
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