EVALUATION OF THE HEAVY METALS CONTAMINATION OF THE WATER OF THE MOULOUYA MEDIUM

This work is part of a program to study and monitor the impact of human activities in the cities of Missour and Outat El Haj on the quality of the surface waters of the average Moulouya (Morocco).The aim of this study is to evaluate in time and space, the degree of metallic pollution of surface water of the average Moulouya during the period (September 2014, January, April and July 2015). The results of this study suggest that the waters of the ten stations in the study area are relatively contaminated with heavy metals. The contents of the analyzed metals are high and variable in the wastewater of the cities of Missour and Outat El Haj and in the waters of the Moulouya average.The anthropogenic impact on the ecosystems selected for this work is highlighted by: the high metallic contamination of the water of the stations located downstream of wastewater discharges of the cities of Missour and Outat El Haj, and the variation of the contents according to an increasing concentration gradient from station M1 to M9.

Screening of metallic pollution in complex environmental samples through a transcriptomic fingerprint method

Characterizing waste ecotoxicity is labourious because of both the undefined nature of environmental samples and the diversity of contaminants that can be present. With regard to these limitations, traditional approaches do not provide information about the nature of the pollution encountered. To improve such assessments, a fluorescent library of 1,870 transcriptomic reporters from E. coli K12 MG1655 was used to report the ecotoxic status of environmental samples. The reliability of the approach was evaluated with 6 metallic pollutants (As, Cu, Cd, Hg, Pb, Zn) used alone and in mixture in pure and complex matrices. A total of 18 synthetic samples were used to characterize the specificity of the resulting metallic contamination fingerprints. Metallic contamination impacted 4.5 to 10.2% of the whole transcriptomic fingerprint of E. coli. The analysis revealed that a subset of 175 transcriptomic reporters is sufficient to characterize metallic contamination, regardless of the nature of the sample. A statistical model distinguished patterns due to metallic contamination and provided information about the level of toxicity with 93–98% confidence. The use of the transcriptomic assessment was validated for 17 complex matrices with various toxicities and metal contaminants, such as activated sludge, wastewater effluent, soil, wood and river water. The presence of metals and their associated toxicity, which seems linked to their bioavailabilities, were thereby determined. This method constitutes a possible tool to screen unknown complex samples for their metallic status and identify those for which a deeper characterization must be achieved by the use of traditional biosensors and analytical methods.

Ficus retusa L. as possible indicator of air metallic pollution in urban environmentSahli Leila, Belhiouani Hadjer

The tree species differed by their capacity to capture air-borne dust and to allocate trace element from contaminated soil. The aim of this study was to explore the accumulation potential of heavy metals (HMs) by F. retusa L. and its possible use for air pollution biomonitoring in urban areas. Plant material was sampled along the national roads in Constantine city (NE-Algeria), characterized by an intense traffic load. The concentrations of cadmium, copper, lead and zinc were determined in the washed and unwashed leaves. The mean concentrations of HMs decrease in the following order: Zn > Pb > Cu > Cd for both studied leaves, and were about 0.68 and 0.98 µg/g for Cd, 7.26 and 8.74 µg/g for Cu, 20.35 and 37.61 µg/g for Pb and 63.33 µg/g and 75.94 µg/g for Zn, for washed/unwashed leaves respectively. The studied metal contents were significantly higher than those cited in the literature; this indicates the traffic road impact on HMs emissions and uptake by plants. Higher values of metal accumulation index (MAI) indicate the effectiveness of the studied species for monitoring air metallic pollution in urban areas, and its usefulness for phytoextraction of HMs from the polluted soils and/or air. Results of this study could be beneficial as preliminary reference values for HMs uptake by F. retusa in urban environments.

Effects of Urbanization on the Degradation of the Palm Grove Around the City of Marrakech

The city of Marrakech is experiencing a very significant development in terms of urbanization which leads to a significant reduction of the agricultural activity and increase of the rate of metallic pollution in soils. The impact of this metallic pollution on the microbial activity in these soils can negatively affect the growth and the development of the date palm (Phoenix dactylifera L). In addition, the urbanization has direct effects on the degradation of palm groves in the Marrakech region, following a decrease in agricultural and forestry productivity after anthropogenic activities which are at the origin of high metallic trace element (MTE) contents in soils. In order to assess the impacts of this pollution, the authors carried out a study in the rhizospheric soils of the date palm (Phoenix dactylifera L) monitoring the levels of heavy metals (Pb, Zn). Eight sites were chosen: five urban sites (three gardens, two boulevards) and two peri-urban sites (palm groves).

Trees as sentinels of metallic pollution induced by mining along the Odiel River (Southern Iberian Peninsula)

Mining activity is often responsible for the drainage of acid or metal-enriched waters to fluvial systems. The release of metals is especially disturbing due to the toxicity and persistence of these products and their accumulation in the biosphere. Hence, a systematic detection and delimitation of highly polluted floodplains and linkages between pollution and high-flow stages would likely assist the improvement of land management and ease the design of mitigation or rehabilitation measures. Here we test how trees growing in different geomorphic positions along a fluvial system uptake metal during floods and how these uptakes can be documented “a posteriori”. To this end, we apply dendrogeochemical analyses to twenty Pinus pinaster Ait. trees growing on the banks of Odiel River (south-western Spain) as well as to five reference trees growing outside the river channel. In the field, trees were sampled with a large-diameter (1 cm) increment borer. In the lab, tree-ring series were dendrochronologically cross dated and separated into 5-yr blocks, so that wood blocks contained the dates of major floods. Then, Inductively Coupled Plasma Mass Spectrometry (ICPM) was employed to evaluate toxic metal concentrations in trees. Results point to clear correlations between the accumulation of toxic metals and the geomorphic position of trees within the fluvial network. We show that morphological units along a river exert control on toxic metal concentrations in trees, with uptake being much higher in trees located on meander cut banks than in trees growing on point-bar structures. Besides, we detect chemical signatures in trees located farthest away from the main river channel after the largest floods, but not in the aftermath of smaller events. We conclude that tree position is the single-most important determinant for metallic pollution in an environment controlled by fluvial processes, but also find that more studies are still needed to determine linkages with individual floods and interactions of metal uptake in roots via the water table in the river corridor.

Assessing Impacts of Metallic Contamination along the Tidal Gradient of a Riverine Mangrove: Multi-metal Bioaccumulation and Biomagnification of Filter-Feeding Bivalves

Most riverine mangroves (characterized by salinity fluctuations and tidal inundations), are seriously threatened by metallic pollution. Whether differences in salinity and tidal effects along the river continuum can affect metallic bioaccumulation and the biomagnification of species is still unknown. Bivalves are representative sessile inhabitants in mangrove ecosystems, with a high capacity to bioaccumulate metallic contaminants. The present study used two bivalves, Meretrix lusoria and Mytilopsis sallei, to monitor inter-site changes in metallic contamination and assess the associated ecological impacts along the tidal gradients of riverine mangroves. The concentrations of a total of six metals (Cr, Ni, Cu, Zn, Cd and Pb) in M. lusoria and M. sallei, collected at three different sites along Danshuei Riverine Mangrove, were investigated. The metallic concentrations of the whole soft body of the studied bivalves, and the associated surface sediment from each site, were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to determine the inter-site effects on the bioaccumulation and biomagnification of metallic contaminants in bivalves. There are increasing concentrations of four metallic contaminants, Zn, Cr, Cd and Cu, in the seaward direction of the bivalves. The increasing mean metallic concentrations along the seaward direction may be the effect of salinity, further decreasing the rate of the elimination of these metals, thus resulting in a net increase in metallic contaminants. Our results clearly show prominent inter-site changes in the metallic burdens of bivalves in our study on riverine mangrove ecosystems associated with different levels of bioaccumulation and biomagnification of metallic contaminants. Thus, it is important to monitor multiple sites along the dynamic environment of riverine mangroves in order to gain a good understanding of the ecological impact of metallic pollution risks. The present findings provide important evidence of the use of simple indices to assess the ecological impacts of metallic pollution in riverine mangroves.