Ecological Risk Assessment of Heavy Metals along Three Main Drains in Nile Delta and Potential Phytoremediation by Macrophyte Plants

Abstract

The use of drainage water in the irrigation of agroecosystem is associated with environmental hazards, and can pose threats to human health. Nine heavy metals (Fe, Mn, Zn, Cu, Co, Cr, Ni, Cd and Pb) along three main drains in the middle Nile Delta were measures in the sediments, roots and shoots of three common macrophytes (Echinochloa stagnina, Phragmites australis and Typha domingensis). The physicochemical characteristics, as well as the enrichment factor (Ef), contamination factor (Cf), geoaccumulation index (Igeo), ecological risk factor (Er), degree of contamination (Dc) and potential ecological risk index (PERI), were determined for sediment. The metal bioaccumulation factor (BAF) and translocation factor (TF) were assessed for plants. Data revealed high contents of Cr, Zn and Cd in the upstream of the drains, while Mn, Cu and Ni were recorded in high concentrations in the downstream. Mn, Cr, Co, Cu, Ni and Zn were recorded to be within EU (2002), CSQGD (2007) and US EPA (1999) limits, while Cd and Pb showed high a ecological risk index. This high concentration of pollutants could be attributed to unremitting industrial activities, which can bioaccumulate in the food chains and cause serious problems for humans. The root of P. australis showed the effective accumulation of most of the elements, while T. domingensis revealed the highest accumulation of Pb. However, the highest BAF shoot value was found in T. domingensis for most of the heavy metals, except for Fe and Zn in P. australis and Mn in E. stagnina. Thus, P. australis could be used as a potential phytoextractor of these hazardous metals, as an eco-friendly and cost-efficient method for remediation of the polluted drains. Further, T. domingensis could be integrated as a hyperaccumulator of Pb. Strict laws and regulations must be taken into consideration by the policymaker against unmanaged industrial activities, particularly near the water streams in the Nile Delta.

Phytoremediation Perspectives of Seven Aquatic Macrophytes for Removal of Heavy Metals from Polluted Drains in the Nile Delta of Egypt

“…In addition, the Fe and Zn concentrations in P. austarlis , E. stagnina and E. crassipes tissues, the Mn concentration in P. australis and E. crassipes tissues, the Co and Ni concentrations in P. austarlis , T. domingensis and E. crassipes tissues were higher than the safe levels in plants (phytotoxic levels of Fe: >500 mg kg −1 , Zn: 100–400 mg kg −1 , Mn: >400 mg kg −1 , Co: 15–50 mg kg −1 and Ni: 10–100 mg kg −1 ) [ 46 ]. These results coincided with those reported in the same species in previous studies [ 5 , 24 , 27 , 40 , 47 ]. The notable high concentrations of most investigated heavy metals in the studied species may be in response to the high concentration and bioavailability of these metals in the sediment in the three drains.…”

“…In the present study, the concentrations of sediment heavy metals were ordered as Fe > Mn > Zn > Cu > Pb > Cd > Ni > Co. These results agree with Fawzy et al [ 24 ] and El-Amier et al [ 40 ], who found a similar pattern of heavy metals distribution in different canals and drains along the Nile River of Egypt. Fe and Mn were the most abundant metals in the sediment in the three drains among the investigated metals.…”

“…The investigated drains contained a higher level of Cd, but lower levels of Ni and Pb, than other drains of the Nile Delta, such as the Kitchener drain that had 4.10 mg kg −1 of Cd, 68.7 mg kg −1 of Ni, and 83.4 mg kg −1 of Pb [ 9 ]. Furthermore, the data of this study indicated that the mean values of the estimated heavy metals were lower than that reported by [ 40 ] for three drains (Elhoks, El-Shakhlouba and Drain 7), [ 45 ] for the Kitchener Drain, and [ 47 ] for contaminated wetlands in Egypt. In addition, Eid et al [ 48 ] recorded 11.9–12.6 mg kg −1 of Ni and 12.7–13.7 mg kg −1 of Pb in the sediment of Burullus Lake of Egypt, which tended to be lower than that estimated in this study.…”

“…In this context, sewage sludge, synthetized fertilizers, paints, dyes, electroplating, steel industries, batteries, pipes, pesticides, soaps, antimicrobial agents, fuel combustion, etc. likely greatly contribute to the raised levels of the studied heavy metals in the studied drains of the Nile River in Egypt [ 19 , 24 , 26 , 40 , 45 ]. On the other hand, the low concentrations of Cd, Ni, and Co might suggest a probable sole natural origin.…”

An analysis of heavy metals contamination and estimating the daily intakes of vegetables from Uganda

“…46,50 At high concentrations, non-essential metals such as Pb and Cd as well as essential metals Zn, Fe, and Cu may play a role in the pathogenesis of diseases such as Alzheimer's disease through oxidative stress mechanisms. [37][38][39] This is particularly important to African descendants who are genetically susceptible to this dementing process. 51 Disproportional deposition of metals in the body promotes the expression of secretases that disrupt organelle function, leading to impairment in function.…”