Spatial distribution and pollution assessment of trace metals in surface sediments of Ziqlab Reservoir, Jordan

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.

Modern sediment records of hydroclimatic extremes and associated potential contaminant mobilization in semi-arid environments: lessons learnt from recent flood-drought cycles in southern Botswana

“…These specific metals were selected because (i) they typically serve as proxies for the assessment of risk related to pollutants (c.f. Al-Taani et al 2015;Zhu et al 2017), and (ii) geological background values were available (from the Transvaal Supergroup and Kanye Formation).…”

“…Both of these translate into a discontinuous sedimentary record. These regions are characterized by extreme climate variability and are subject to droughts and heavy, discontinuous rainfall periods often followed by floods (Bisantino et al 2011;Al-Taani et al 2015). It is paramount to avoid gaps in sampling of hydrometric and meteorological data to ensure same or similar detail in water quantity and quality on the one hand and sediment records the other.…”

“…These regions are characterized by extreme climate variability and are subject to droughts and heavy, discontinuous rainfall periods often followed by floods (Bisantino et al 2011;Al-Taani et al 2015). In arid to semi-arid environments, even the long-awaited rain after a prolonged dry season can become a threat, especially if it comes as an "exceptionally" intense rainfall event (Tsheko 2003;Ghazavi et al 2012;Al-Taani et al 2015;Alemaw et al 2016). In fact, in this environment, the high intensity and short duration of rainfall causes extensive runoff and floods (e.g., Ghazavi et al 2012).…”

“…As a result, sediment yields might be larger compared to more humid environments (Goode et al 2012). In semi-arid environments, the amount of precipitation is sufficient to produce soils but not in sustaining the vegetation required to stabilize the hillslopes throughout the year, resulting in enhanced erosion during heavy rains (Bisantino et al 2011;Goode et al 2012;Al-Taani et al 2015) with high suspended sediment concentrations in rivers during floods (Megnounif et al 2007;Bisantino et al 2011). Hence, storm intensity and duration are important controls on the sediment production in semi-arid basins, and therefore, climate-driven variations are likely to produce changes in sediment yields (e.g., Goode et al 2012).…”

Optimizing the Crystal Habit of Glycine by Using an Additive for Impinging Jet Crystallization

“…Parameters such as the concentration and type of the additives can influence the occurrence of the different polymorphs [20][21][22]. The additives used for the crystallization process can influence the dissolution rate, the hardness, and therefore even the efficiency of the tablets [23][24][25].…”