Fares M. Howari

Assessment of Fe, Zn, Cd, Hg, and Pb in the Jordan and Yarmouk River Sediments in Relation to Their Physicochemical Properties and Sequential Extraction Characterization

Forty-six surface sediment samples taken along the beds of boththe Jordan and Yarmouk Rivers were analysed for Pb, Cd, Zn, Fe andHg by atomic absorption spectrophotometer. Extraction techniqueswere used to establish the association of the total concentrations of Pb, Cd, Zn and Fe in the sediment samples withtheir contents in the exchangeable, carbonate, Fe/Mn oxides, organic and residual fractions.In the sediments of the Jordan River the recorded heavy metalsconcentrations were as follow: 8.1 ppm for Pb, 0.63 ppm for Cd, 20.3 ppm for Zn, 6 ppm for Hg and 1265.6 ppm for Fe; whereas in the sediment of Yarmouk River were 8.4 ppm for Pb, 0.67 ppm for Cd, 26.4 ppm for Zn, 6.2 ppm for Hg and 1370 ppmfor Fe. Pb, Cd, Zn, and Fe concentrations in the sediments ofboth rivers reflect the natural background value in shale, whereas Hg is moderately enriched. I-geo (geo-accumulation index) of metals in the sediments under study indicates thatthey are uncontaminated with Pb, Zn and Fe; contaminated tomoderately contaminated with Cd; and strongly contaminated with Hg. Heavy metal content in the sediments were found to be significantly influenced by different physico-chemical parameters. The effect of these physico-chemical parameters canbe arranged in the following order: clay fraction > organicmatter fractions > carbonate fraction > silt fraction. As sequential extraction procedure shows that the total concentration of the heavy metals are largely bound to the residual phase (retained 79.5% of Pb, 38% of Cd, 54.4% of Zn and 51.6% of Fe in Jordan River Sediments; and 88.6% of Pb, 48.2% of Cd, 37.6% of Zn and 59.5% of Fe in the YarmoukRiver sediments). The following sequence of mobility are suggested: Fe > Cd > Zn > Pb in Jordan River sediments, and Fe > Zn > Cd > Pb. in Yarmouk River sediments.

The use of remote sensing data to extract information from agricultural land with emphasis on soil salinity

The rapid growth of information technologies has provided exciting new sources of data, interpretation tools, and modelling techniques to soil research and education communities at all levels. This paper presents some examples of the capability of remote sensing data such as Landsat ETM+, airborne visible/infrared imaging spectrometer (AVIRIS), colour infrared aerial photos (CIR), and high-resolution field spectroradiometer (GER 3700) to extract surface information about soil salinity. The study used image processing techniques such as supervised classification, spectral extraction, and matching techniques to investigate types and occurrences of salts in the Rio Grande Valley on the United States–Mexico border. Soil salinity groups were established using soil physico-chemical properties and image elements (absorption-reflectivity profiles, band combinations, grey tones of the investigated images, and textures of soil and vegetation covers as they appear in images). The lack of vegetation or scattered vegetation on salt-affected soil (SAS) surfaces makes it possible to detect salt in several locations of the investigated area. The presented remote sensing datasets reveal the presence of gypsum and halite as the dominant salt crusts in the Rio Grande Valley. This information can help agricultural scientists and engineers to produce large-scale maps of salt-affected lands, which will help improve salinity management in watersheds and ecosystems.

Investigation of Hydrocarbon Pollution in the Vicinity of United Arab Emirates Coasts Using Visible and Near Infrared Remote Sensing Data

Abstract Influx of hydrocarbon contaminants to the coasts of United Arab Emirates is a serious environmental problem that threaten marine habitat. This paper presented two datasets to extract information on hydrocarbon pollution in marine environment utilizing visible to near infrared portion of the electromagnetic spectrum. The datasets used were Land-sat ETM+ images for Dubai and Fujirah coasts, and experimental visible to near infrared spectra of petroleum hydrocarbon in water. The experimental spectra were measured using GER 3700 spectroradiometer. The study applied image analyses techniques and radiance ratios on corrected Landsat ETM+ images in order to detect oil spills from tankers. The reported results demonstrated proper bands or channels with techniques useful for oil spill detection using images of Landsat ETM+. The study found that radiances extracted from visible and near infrared images are useful to assess the thickness of hydrocarbon spills. The study also found that areas of thicker oil are slightly brighter because they suppress the signal from the underlying seawater. The spectra of GER 3700 provide potentials for identification of possible contaminants as well as classification within a particular hydrocarbon category (e.g. aromatics). The presented techniques hold promise for rapid analysis of petroleum hydrocarbons in marine environment.

Field and Remote-Sensing Assessment of Mangrove Forests and Seagrass Beds in the Northwestern Part of the United Arab Emirates

Abstract Mangrove stands and seagrass beds grow along the coasts of the United Arab Emirates (UAE). These marine plant species are concentrated in specific tidal zones along sheltered intertidal coastlines in association with estuaries and lagoons; mangroves fringe the coastline encroaching into the lower intertidal region, whereas seagrasses populate the adjacent deeper water. In most cases, the distribution of mangroves and seagrasses does not overlap. It is important to monitor the geographic extent and health of mangrove forests and seagrass beds, which serve as an important habitat for juvenile marine species. Remote-sensing data for the Khor Al Bazam area in the vicinity of Abu Dhabi, UAE, covering the years of 1994, 2000, and 2003, were used to determine the change in mangrove and seagrass cover. Since 1994, there has been an increase in mangrove cover, likely because of plantation activity, the closure of nearby shipyards, and an increase in public awareness regarding mangrove preservation. Although more difficult to determine, a combination of remote sensing and ground-truthing indicates that the seagrass beds within the study area have likely increased in real extent over the same time period.

Heavy metal pollution of soils along North Shuna-Aqaba Highway, Jordan

Attention to heavy metal contamination associated with highways or motorways has risen in the last decades because of the associated health hazards and risks. The present study analysed the metal content in soil samples of one of the main highways along the western part of the Jordanian border, the North Shuna-Dead Sea-Aqaba Highway. The metals analysed were Pb, Zn, Cd, Co and Ni. In the samples collected, the recorded average concentrations were as follows: 40 ppm for Ni, 5 ppm for Cd, 79 ppm for Zn, 79 ppm for Pb, and 25 ppm for Co. The average concentrations of Cd, Pb, and Co are higher than the average natural background values of heavy metals. The geo- accumulation index of these metals in the soils under study indicated that they are uncontaminated with Ni, Zn, and Co and moderately contaminated with Cd and Pb. In all of the investigated locations, the study found that concentrations decreased with depth. The cluster statistical analyses and pollution load index were used to relate pollution to land use or highway conditions. Two main trends were identified: (i) higher concentrations were located near intersections close to the urban areas in the Jordan Valley, in association with junctions controlled by traffic lights and check points, and (ii) lower concentrations were found to the southwest in areas of mainly barren landscape close to the Dead Sea and Aqaba.

Chemical Fractionation and Heavy Metal Distribution in Agricultural Soils, North of Jordan Valley

Thirty-nine soil samples were collected on a grid pattern from the north of the Jordan Valley. These samples were subjected to geochemical, mineralogical and textural analyses. The investigated soil is characterized by medium texture and to a less extent moderately coarse and coarse texture. The value of TDS shows a slight increase in the southern part of the study area toward the Dead Sea due to the increase in temperature and decrease of the amount of precipitation. The organic matter content and P 2 O 5 values show significant variations that coincide with agricultural activity and application of fertilizers and pesticides in the investigated area. In the samples collected, CEC values are slightly decreased from north to south parts of the study area where the abundance of organic matter and clay minerals are low. The study found that the enrichment factors of the measured heavy metals Pb, Cd, As and Hg are 2.8, 11.9, 20 and 17 respectively. Accordingly, the soil of the study area can be considered moderately contaminated with respect to As and Hg and uncontaminated to moderately contaminated with respect to Pb and Cd. The distribution of the measured heavy metals are affected by various geochemical factors including pH, clay content, cation exchange capacity, organic matter content and total phosphate content. Sequential extraction procedure was used in order to determine the percentage of the Pb, Cd and As present in five geochemical fractions of the examined soil samples. It was found that Pb and As are mainly associated with the residual phases and are relatively immobile. On the other hand Cd is enriched in the carbonate phase of the analyzed soil samples. Based on the sequential extraction procedure it is possible to suggest the sequence of metal mobility as: Cd > Pb > As.

Heavy metal speciation and mobility assessment of arid soils in the vicinity of Al Ain landfill, United Arab Emirates

Sixty-four surface soil samples taken in the vicinity of Al Ain landfill were analysed for cadmium, chromium, copper, nickel, lead and zinc by inductively coupled plasma spectroscopy. Extraction techniques were used to establish the association of the total concentrations of the six metals in the soil samples with their contents in the exchangeable, carbonate, iron/manganese oxides, and residual fractions. In the investigated soils, the recorded concentrations were as follows: 0.043 mg kg-1 for cadmium, 19.1 mg kg-1 for chromium, 53.3 mg kg-1 for copper, 60 mg kg-1 for nickel, 13.7 mg kg-1 for lead, and 117 mg kg-1 for zinc. Cadmium, chromium, nickel, lead and zinc concentrations in the investigated soil samples reflect the natural background values in shale, whereas copper is slightly enriched. I-geo (geoaccumulation index) values of the metals in the soils under study indicate that they are uncontaminated with cadmium, chromium, nickel, lead and zinc, but contaminated to moderately contaminated with copper. Heavy metal contents in the sediments were found to be significantly influenced by different physico-chemical parameters. The effect of these parameters can be arranged in the following order: clay fraction > carbonate fraction > silt fraction > organic matter fractions. A sequential extraction procedure showed that the total concentrations of the heavy metals are largely bound to the residual phase (retained 71.4% of cadmium, 77.8% of chromium, 75% of copper, 47% of nickel, 62.8% of lead, and 75.8% of zinc). A likely sequence of mobility in the investigated soils is as follows: chromium > lead > nickel > cadmium > zinc > copper.

Remote Sensing and Spectral Characteristics of Desert Sand from Qatar Peninsula, Arabian/Persian Gulf

Remote sensing data can provide valuable information about the surface expression of regional geomorphologic and geological features of arid regions. In the present study, several processing techniques were applied to reveal such in the Qatar Peninsula. Those included preprocessing for radiometric and geometric correction, various enhancement methods, classification, accuracy assessment, contrast stretching, color composition, and principal component analyses. Those were coupled with field groundtruthing and lab analyses. Field groundtruthing included one hundred and forty measurements of spectral reflectance for various sediment exposures representing main sand types in the four studied parts in Qatar. Lab investigations included grain size analysis, X-ray diffraction and laboratory measurements of spectral reflectance. During the course of this study three sand types have been identified: (i) sabkha-derived salt-rich, quartz sand, and (ii) beach-derived calcareous sand and (iii) aeolian dune quartz. Those areas are spectrally distinct in the VNIR, suggesting that VNIR spectral data can be used to discriminate them. The study found that the main limitation of the ground spectral reflectance study is the difficulty of covering large areas. The study also found that ground and laboratory spectral radiance are generally higher in reflectance than those of Landsat TM. This is due to several factors such as atmospheric conditions, the low altitude or different scales. Whereas for areas with huge size of dune sand, the Landsat TM spectral has higher reflectance than those from field and laboratory. The study observed that there is a good correspondence or correlation of the wavelengths maximum sensitivity between the three spectral measurements i.e lab, field and space-borne measurements.

Water Chemical Characteristics of the Red Sea Coastal Sabkhas and Associate Evaporite and Carbonate Minerals

Abstract “Sabkha” is a term used to describe the coastal flats and salt marches deposited in lagoonal areas under arid conditions. In this study, water and sediment samples (n = 51 and 182, respectively) were collected from sabkhas systems of the Red Sea coast, which extends between Jeddah city and the town of Yanbu Al-Bahar and is bounded by latitudes 21°30′ and 24°00′N and longitudes 38°00′ and 39°30′E. The collected sediment samples were subjected to sedimentological and mineralogical analyses using grain size and X-ray diffraction techniques. The water samples were subjected to hydrochemical analyses using several standard procedures. The study found that climatic conditions in the Red Sea coastal plain sabkhas lead to the formation of marine brines of magnesium-sodic to chloride type with neutral pH value. Because of the evaporation of the groundwater, the evaporite minerals, especially aragonite, halite, and gypsum, were precipitated. The present study shows that this resulted in an increase in the Mg+2/Cl−1 ion concentrations and the formation of protodolomite mainly in the sediments of the supratidal flats. The reported results indicate that the precipitation of the evaporite minerals and the early diagenetic dolomitization caused decrease in sulfate concentration and the Mg+2/Ca+2 ratios in the water of the supratidal flats. The study also found that more than 50% of the Na+1 ions were precipitated as halite as indicated from the average value of Na+1/Cl−1 ratios, which is lower than 0.75. The absence of clay beds in the sediments overlying the water table is probably the reason for the similar potassium ion concentrations in both upper intertidal and supratidal flat waters in addition to the Red Sea water. The relatively low concentrations of sulfates in the water of the supratidal flats of the studied sabkhas in comparison with their concentrations in the water of the upper intertidal flats are probably due to the precipitation of gypsum in the sediments of the supratidal flats of these sabkhas. The slightly high concentrations of bicarbonates in the water of the studied sabkhas are due mainly to the precipitation of carbonates, especially aragonite, as well as to the low pH values of these waters. The reported results can be considered as documentation of the hydrogeochemical characteristics of the Red sea sabkhas and could be useful for planners and researchers interested in the Red Sea coastal systems.

Distribution of heavy metals in the coastal area of Abu Dhabi in the United Arab Emirates

Fifty-seven sediment samples were collected from Abu Dhabi coastal area, United Arab Emirates (UAE). The concentrations of heavy metals including antimony, arsenic, barium, cadmium, cobalt, copper, mercury, lead, molybdenum, nickel and zinc were obtained using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) and X-ray fluorescence. Heavy metal contaminations in Abu Dhabi had increased since 2004. Nevertheless, the enrichment factors, geoaccumulation indices and the pollution load index of 0.3 showed no pollution with any of the measured metals except arsenic.