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1.
Environ Sci Process Impacts ; 25(8): 1347-1364, 2023 Aug 16.
Article in English | MEDLINE | ID: mdl-37401332

ABSTRACT

Microplastics (MPs) are emerging pollutants of global concern due to their pervasiveness, high sorption ability for persistent organic pollutants (POPs) and direct and indirect toxicity to marine organisms, ecosystems, as well as humans. As one of the major coastal interfaces, beaches are considered among the most affected ecosystems by MPs pollution. The morphological characteristics of MPs (pellets and fragments) collected from four beaches along the Tunisian coast and sorbed POPs, including polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), were investigated in this study. The results showed that the MPs varied greatly in color, polymer composition and degradation degree. The color varied from colored to transparent and the most prevalent polymer identified using Raman spectroscopy was polyethylene. Scanning electron microscope (SEM) images exhibited various surface degradation features including cavities, cracks, attached diatom remains, etc. The concentrations of Σ12PCBs over all beaches ranged from 14 to 632 ng g-1 and 26 to 112 ng g-1 in the pellets and fragments, respectively, with a notable presence and dominance of highly-chlorinated PCBs such as CB-153 and -138. Among the OCPs, γ-HCH is the only compound detected with concentrations ranging from 0.4 to 9.7 ng g-1 and 0.7 to 4.2 ng g-1 in the pellets and fragments, respectively. Our findings indicate that MPs found on the Tunisian coast may pose a chemical risk to marine organisms as the concentrations of PCBs and γ-HCH in most of the analysed samples exceeded the sediment-quality guidelines (SQG), especially the effects range medium (ERM) and the probable effects level (PEL). As the first report of its kind, the information gathered in this study can serve as the baseline and starting point for future monitoring work for Tunisia and neighbouring countries, as well as for stakeholders and coastal managers in decision-making processes.


Subject(s)
Environmental Pollutants , Hydrocarbons, Chlorinated , Pesticides , Polychlorinated Biphenyls , Water Pollutants, Chemical , Humans , Ecosystem , Environmental Monitoring/methods , Environmental Pollutants/analysis , Hexachlorocyclohexane/analysis , Hydrocarbons, Chlorinated/analysis , Mediterranean Sea , Microplastics , Persistent Organic Pollutants , Pesticides/analysis , Plastics/analysis , Polychlorinated Biphenyls/analysis , Tunisia , Water Pollutants, Chemical/analysis , Animals
2.
Sci Total Environ ; 660: 660-676, 2019 Apr 10.
Article in English | MEDLINE | ID: mdl-30641395

ABSTRACT

The increasing contamination of fresh water resources by trace metals and persistent organic pollutants is a major environmental concern. In the present study, we investigated, for the first time, the distribution, sources and ecological risk of trace metals and organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), in surface sediments from a Southeastern European river (Somesu Mic River, Romania). Concentrations of Cd, Cr, Cu, Pb, Ni and Zn ranged from 0.04 to 0.4, 9.4 to 43.15, 7.2 to 65.6, 12.3 to 131.4, 14.7 to 47.7 and 42.1 to 236.8 mg kg-1 dw, respectively. Concentrations of total PAHs, PCBs and OCPs ranged from 24.8 to 575.6, 2.7 to 252.7 and 2.1 to 44.3 ng g-1 dw, respectively. Some sediment parameters, i.e., pH, total organic carbon (TOC) and total organic matter (OM) contents, played a significant role in the spatial distribution of contaminants. A combined analysis based on diagnostic ratios and multivariate analyses revealed PAHs originating mainly from pyrolytic sources. PCB compositions showed distinct contamination signatures for tri- to tetra-chlorinated PCBs, characteristic of contamination by Aroclor-1016 and -1254 technical mixtures. The dominant OCP congeners were α-HCH and p,p'-DDD, reflecting past use of technical HCHs and DDTs in agricultural practices. Metal source and pollution status was assessed using geoaccumulation index and enrichment factor, which indicate widespread pollution by Pb, Cd, Zn, Ni and Cu. The use of Sediments Quality Guidelines (SQGs), mean effect range-median quotient (m-ERM-Q) and toxic equivalent factor (TEF) indicated that the highest ecological risks occurred for PCBs and DDTs. This work presents not only initial baseline information on the extent of organic and inorganic contaminations in a river of ecological and economical interest, but also provides a diagnostic ratio/statistical combined approach that can be used to evaluate sediment quality in similar environments.

3.
Sensors (Basel) ; 17(10)2017 Oct 18.
Article in English | MEDLINE | ID: mdl-29057847

ABSTRACT

Landslides are major and constantly changing threats to urban landscapes and infrastructure. It is essential to detect and capture landslide changes regularly. Traditional methods for monitoring landslides are time-consuming, costly, dangerous, and the quality and quantity of the data is sometimes unable to meet the necessary requirements of geotechnical projects. This motivates the development of more automatic and efficient remote sensing approaches for landslide progression evaluation. Automatic change detection involving low-altitude unmanned aerial vehicle image-based point clouds, although proven, is relatively unexplored, and little research has been done in terms of accounting for volumetric changes. In this study, a methodology for automatically deriving change displacement rates, in a horizontal direction based on comparisons between extracted landslide scarps from multiple time periods, has been developed. Compared with the iterative closest projected point (ICPP) registration method, the developed method takes full advantage of automated geometric measuring, leading to fast processing. The proposed approach easily processes a large number of images from different epochs and enables the creation of registered image-based point clouds without the use of extensive ground control point information or further processing such as interpretation and image correlation. The produced results are promising for use in the field of landslide research.

4.
Ecotoxicology ; 25(6): 1082-104, 2016 Aug.
Article in English | MEDLINE | ID: mdl-27146821

ABSTRACT

The present study investigates the quality of surface sediments from the Bizerte lagoon (North Tunisia) using an integrated approach including chemical contaminant analysis, bioassays and sediment quality guidelines (SQGs). Sediment samples were collected at 9 sites and analyzed for eight heavy metals (Hg, Cd, Cr, Cu, Pb, Zn, Ni, Fe and Mn). PAHs, PCBs, OCPs were measured previously in the same sediment samples. Our results indicated that the highest concentrations of metals were found near urban areas due to the municipial and industrial wastewater discharges. Sediment pollution assessment was carried out using geoaccumulation index and enrichment factor, which indicate a widespread pollution by Cd, Pb, Ni and Zn in the studied sediments. For bioassays, aqueous and organic extracts were used to assess toxicity and genotoxicity in sediments by using Microtox(®) and SOS Chromotest, respectively. Toxicity levels were compared to metallic and organic pollutants contents. Our results highlight differences in the pattern of responses between the different assays and show no correlation with all the studied contaminants, emphasizing the influence of other contaminants not analyzed in the present study. Based on SQGs, the results of toxicity assessment indicated that adverse effects caused by Ni and Zn would be expected frequently. Nickel was found to have the highest predicted acute toxicity, followed by Zn, Pb, Cd, Cu and Cr. There was no significant relationship between sediment toxicity calculated from heavy metal concentrations (SQG approach) and those measured with bioassays. These findings support the use of integrated approachs for evaluating the environmental risks of sediments.


Subject(s)
Environmental Monitoring/methods , Geologic Sediments/chemistry , Water Pollutants, Chemical/analysis , Metals, Heavy/analysis , Polychlorinated Biphenyls/analysis , Polycyclic Aromatic Hydrocarbons/analysis , Seawater/chemistry , Tunisia
5.
Environ Monit Assess ; 187(2): 32, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25632906

ABSTRACT

Surface sediment samples were collected from Ziqlab dam in northwestern Jordan to investigate the spatial distribution of selected trace metals and assess their pollution levels. The results showed that the concentrations of Pb, Cd, and Zn exceeded the environmental background values. Cd, Ni, and Cr contents were higher than the threshold effect level (TEL) in 63, 83, and 60 % of the reservoir sediments, respectively; whereas Pb, Zn, and Cu were less than the TEL limit. The concentrations of trace metals in reservoir sediment varied spatially, but their variations showed similar trends. Elevated levels of metals observed in the western part (adjacent to the dam wall) were coincided with higher contents of clay-silt fraction and total organic matters. Multivariate analysis indicated that Pb, Co, and Mn may be related to the lithologic component and/or the application of agrochemicals in the upstream agricultural farms. However, Cd and Zn concentrations were probably elevated due to inputs from agricultural sources, including fertilizers. Evaluation of contamination levels by the Sediment Quality Guidelines of the US-EPA, revealed that sediments were non-polluted to moderately polluted with Pb, Cu, Zn, and Cr, but non-polluted to moderately to heavily polluted with Ni and non-polluted with Mn. The geoaccumulation index showed that Ziqlab sediments were unpolluted with Pb, Cu, Zn, Ni, Cr, Co, and Mn, but unpolluted to moderately polluted with Cd. The high enrichment values for Cd and Pb (>2) indicate their anthropogenic sources, whereas the remaining elements were of natural origins consistent with their low enrichment levels.


Subject(s)
Environmental Monitoring , Geologic Sediments/chemistry , Metals/analysis , Water Pollutants, Chemical/analysis , Agriculture , Jordan , Multivariate Analysis
6.
Environ Monit Assess ; 185(2): 1847-58, 2013 Feb.
Article in English | MEDLINE | ID: mdl-22644122

ABSTRACT

Over the last several decades, there has been increased attention on the heavy metal contamination associated with highways because of the associated health hazards and risks. Here, the results are reported of an analysis of the content of metals in roadside dust samples of selected major highways in the Greater Toronto Area of Ontario, Canada. The metals analysed are lead (Pb), zinc (Zn), cadmium (Cd), nickel (Ni), chromium (Cr), copper (Cu), manganese (Mn), calcium (Ca), potassium (K), magnesium (Mg) and iron (Fe). In the samples collected, the recorded mean concentrations (in parts per million) are as follows: Cd (0.51), Cu (162), Fe (40,052), Cr (197.9), K (9647.6), Mg (577.4), Ca (102,349), Zn (200.3), Mn (1202.2), Pb (182.8) and Ni (58.8). The mean concentrations for the analysed samples in the study area are almost all higher than the average natural background values for the corresponding metals. The geo-accumulation index of these metals in the roadside dust under study indicates that they are not contaminated with Cr, Mn and Ca; moderately contaminate with Cd and K; strongly contaminated with Fe and Mg; strongly to extremely contaminated with Ni and Pb; and extremely contaminated with Cu and Zn. The pollution load index (PLI) is used to relate pollution to highway conditions, and the results show that PLI values are slightly low at different samples collected from Highways 401 and 404 and high in many samples collected from Highway 400 and the Don Valley Parkway. Highway 400 exhibits the highest PLI values.


Subject(s)
Automobiles , Dust/analysis , Environmental Monitoring , Metals, Heavy/analysis , Soil Pollutants/analysis , Cadmium/analysis , Chromium/analysis , Copper/analysis , Environmental Pollution/statistics & numerical data , Iron/analysis , Manganese/analysis , Nickel/analysis , Ontario , Zinc/analysis
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