Int. J. Aquat. Biol. (2023) 11(1): 34-40 ISSN: 2322-5270; P-ISSN: 2383-0956 Journal homepage: www.ij-aquaticbiology.com © 2023Iranian Society of Ichthyology Original Article Short-term assessment of heavy metals in surface waters of the Shatt Al-Arab River Ghassan A. Al-Najar, Abdulkareem T. Yesser, Amir A. Jabir, Kadhim H. Younis Marine Science Center, University of Basrah, Basrah, Iraq. s Article history: Received 24 October 2022 Accepted 19 December 2022 Available online 2 5 February 2023 Keywords: Heavy metals Salinity Seawater intrusion Shatt Al-Arab Surface water Abstract: The Shatt Al-Arab River's water quality deteriorates naturally due to salinity intrusion, and freshwater sources decrease. Seven sampling locations along the Shatt Al- Arab River in southern Iraq were used to examine the level of six heavy metals, including Cu, Cd, Ni, Co, Mn, and Fe, during Januar-December 2021. Salinity levels in the study area ranged from 1.55 upstream to 35.15 g/L downstream of the study area. The pH of surface water ranged 7.545-8.325, indicating alkaline conditions. The concentrations of six heavy metals, viz Cu, Cd, Ni, Mn, Co, and Fe in the study area were 3.741±4.219, 3.654±4.169, 7.700± 6.251, 2.551±3.898, 2.292±3.996, and 18.236±5.583 µg/L, respectively, which decreased in the order of Fe > Ni > Cu > Cd > Mn > Co. There was a considerable change in the quantity of heavy metals throughout the year, with the summer months having the highest concentration. There is a correlation between seawater intrusion and the concentration of heavy metals in the surface waters. The mean levels of the heavy metals were below the allowed values of WHO drinking water guidelines. Introduction Increasing heavy metals in river ecosystems is a significant global issue. Over the last decades, there has been a significant rise in the quantity of heavy metals in river water (Mishra et al., 2022). The Shatt Al-Arab River starts at the confluence of the Tigris and Euphrates Rivers in Qurna, North of Basrah, Iraq, and flows approximately 200 km northwest of the Iraqi marine waters, south of the Al-Fao city (Aldoghachi, 2022). The river width ranges from 250 to 300 m, close to the Euphrates and Tigris confluence to about 700 m in Basrah and over 800 m close to its estuary (Abduljaleel et al., 2020). Its salinity varies greatly depending on the season and quantity of freshwater discharge (Abdallah, 2016). Abduljaleel et al. (2020) reported that the salinity of the water in the Euphrates, Tigris, and Shatt Al-Arab rivers dramatically increased over time. They emphasize how the lack of efficient river basin management programs causes the water quality of Correspondence: Ghassan A. Al-Najar DOI: https://doi.org/10.22034/ijab.v10i6.1784 E-mail: ghassan.kamel@uobasrah.edu.iq DOR: https://dorl.net/dor/20.1001.1.23830956.2023.11.1.5.5 the Euphrates, Tigris, and Shatt Al-Arab rivers to deteriorate. The Shatt Al-Arab estuary and its upstream encountered increasing saltwater intrusion from the Iraqi marine waters, which has a negative impact on ecosystem productivity. Studies on the effects of urban contamination from the city and industry on the Shatt Al-Arab surface water in the Basrah region have been studied (Douabul et al., 2013; Al-Aboodi, 2018). Moyel (2014) used a water quality index to assess the water quality of the northern Shatt Al-Arab region to determine its suitability for drinking, irrigation, and aquatic life. Lafta (2014) and Abdallah (2016) calculated the upstream flow to predict seawater intrusion into Shatt Al-Arab, and it was only suitable for irrigation purposes. Salt concentrations are higher than those permitted for a particular use of water should be categorized as pollutants (Karamouz et al., 2003). Under the influence of geochemical processes, heavy metal contamination will transfer 35 Int. J. Aquat. Biol. (2023) 10(1): 34-40 with surface water and contaminate soil and water directly or indirectly (Liu et al., 2018). However, most works focus primarily on the characteristics of heavy metal contamination in soil and pay little attention to heavy metal pollutants transfer in surface water. It is difficult to identify the distribution characteristics of heavy metals in agricultural ecosystems because of the integrated and cohesive substrate in the surrounding ecosystems (Lermi et al., 2020). Excessive pollutant discharge into surface rivers has caused major decreases in aquatic environmental indicators in recent years (Liu et al., 2016). In this study, the Shatt Al-Arab River is assessed regarding the influence of seawater intrusion from the Iraqi marine water on the concentrations of heavy metals with the main objective of assessing the levels of heavy metals (Cu, Cd, Ni, Co, Mn and Fe) in the surface waters of the Shatt al-Arab based on temporal and spatial variability. Materials and methods The main source of freshwater in Basrah is Shatt Al- Arab, with about 200 km long and an estuary with a three km width. Shatt Al-Arab extends 63 km till reaching Al-Fao. In the Basrah region, it provides services for industry, agriculture, navigation, and ecosystem biodiversity. Numerous small waterways branch out of both banks of the river in Basrah City; most waterways are used for agriculture. Table 1 shows the locations of the monitoring sites in this study. Seven sampling sites in the Shatt Al-Arab River were set up, and each site was positioned with a Global Position System (GPS) to ensure the representativeness of the collected samples. The seven sampling sites were Fao (sea area) (ST1), Fao city (ST2), Abu Al-Khaseeb (ST3), Basrah city (ST4), Sidebad Island (ST5), Hartha (ST6), and Qurna (ST7). Surface water samples were taken at a depth of 30 cm in the middle of the river using a plastic bottle with a one-liter capacity that was fully filled. Water samples were collected monthly (January-December 2021), divided into 6 periods: January-February (P1), March-April (P2) May-June (P3), July-August (P4), September-October (P5), and November- December (P6). One-liter polypropylene sample containers were used to hold the water samples, which had been cleaned three times in distilled water. To prevent water evaporation, all the water samples were parafilm-sealed after being fixed with HNO3 to a pH<2. (APHA, 2005). The water temperature, salinity, and pH at the study sites were measured using a portable multi-meter water quality instrument (YASI, USA). The sample waters were transferred to the laboratory, kept in a low- temperature incubator, and then examined for the presence of heavy metals. All samples were filtered using a 0.45 m cellulose acetate membrane filter to remove contaminants. The concentrations of heavy metals viz. Co, Ni, Cu, Cd, Mn, and Fe were measured using an atomic flame absorption spectrum technique at wavelengths of 248.3, 228.8, 240.7, 279.5, 264.88, and 324.8 nanometers, respectively. Results The water quality of the Shatt Al-Arab River deteriorates naturally due to salinity intrusion, and freshwater sources decrease. Salinity levels in the study area ranged from 1.55 (ST7) to 35.15 gm/L (ST1). The pH of surface water samples ranged between 7.545 to 8.325, indicating alkaline conditions in all studied sites (Table 2). While the temperature ranged between 14.85°C in the winter and 29.55°C in the summer months. The concentration of heavy metals (µg/L) in the study area is shown in Table 3. Heavy metals were found in all the surface water Station Name E N ST1 Fao (sea) 48°48'20.74" 29°47'36.81" ST2 Fao city 48°29'31.07" 29°58'43.92" ST3 Abu Al-Khaseeb 47°54'12.59" 30°28'41.65" ST4 Basrah city 47°48'49.03" 30°33'6.97" ST5 Sidebad Island 47°46'43.38" 30°34'20.80" ST6 Hartha 47°44'47.87" 30°41'41.25" ST7 Qurna 47°27'8.93" 30°59'5.50" Table 1. Monitoring stations and their coordinates. 36 Al-Najar et al./ Short-term assessment of heavy metals in surface waters of the Shatt Al-Arab River Sampling sites Water quality Periods P1 P2 P3 P4 P5 P6 ST1 Temperature(°C) 15.35 17.55 27.3 29.05 27.145 17.16 Salinity (gm/L) 34.35 34.75 34.4 35.15 19.53 17.73 pH 7.65 7.85 8.05 7.81 7.795 7.76 ST2 Temperature(°C) 15.56 18.35 27.65 29.55 27.51 17.37 Salinity (gm/L) 21.85 22.75 23.4 31.55 18.25 17.53 pH 7.80 8.06 8.05 7.80 7.59 7.88 ST3 Temperature(°C) 18.15 21.99 26.85 29.45 17.57 17.19 Salinity (gm/L) 5.91 5.25 5.17 16.32 22.25 15.23 pH 7.96 8.14 7.66 7.82 7.595 7.88 ST4 Temperature(°C) 15.82 21.95 26.65 28.69 27.14 17.09 Salinity (gm/L) 3.82 4.105 5.15 14.08 16.53 16.32 pH 7.54 8.27 7.89 7.83 7.795 7.88 ST5 Temperature(°C) 15.82 21.86 25.97 29.52 27.90 17.465 Salinity (gm/L) 3.43 3.91 4.69 14.41 15.61 13.05 pH 7.54 8.325 7.68 7.84 7.75 7.955 ST6 Temperature(°C) 14.85 20.65 26.25 28.21 27.55 17.15 Salinity (gm/L) 1.99 2.865 3.85 27.26 14.28 12.35 pH 7.62 8.26 7.65 7.86 7.78 7.97 ST7 Temperature(°C) 16.54 21.3 26.6 29.15 28 17.8 Salinity (gm/L) 1.55 1.85 2.94 5.31 4.22 3.18 pH 7.65 8.14 7.65 7.95 7.85 8.03 Table 2. Water quality in surface water of the Shatt Al-Arab River at different locations and times during study period. Sampling Time Sampling Site Heavy metals concentration µg L-1 Cu Cd Ni Mn Co Fe January-February (P1) ST1 12.5 12.45 12.5 12.31 9.33 25.36 ST2 7.52 4.65 18.66 2.09 ND 17.968 ST3 3.54 1.23 20.52 1.42 1 24.169 ST4 1.77 0.615 10.26 0.71 0.5 18.282 ST5 1.18 1.23 0.41 0.4733 0.3333 12.686 ST6 0.885 0.3075 5.13 0.355 0.25 11.792 ST7 0.708 0.246 4.104 0.284 0.2 11.23 March-April (P2) ST1 13.15 12.815 13.26 11.305 12.605 24.185 ST2 3.44 4.685 18.31 1.33 1.555 19.864 ST3 2.515 2.145 16.265 1.54 1.525 26.719 ST4 1.2575 1.0725 8.1325 0.77 0.7625 20.212 ST5 0.8383 2.145 0.715 0.5133 0.5083 14.024 ST6 0.6288 0.5363 4.0663 0.385 0.3813 13.036 ST7 0.503 0.429 3.253 0.308 0.305 12.415 May-June (P3) ST1 12.1 12.63 15.32 12.11 12.41 29.08 ST2 3.24 9.21 21.12 2.32 1.52 19.728 ST3 1.78 4.25 9.23 2.04 1.01 26.536 ST4 0.89 2.125 4.615 1.02 0.505 20.073 ST5 0.5933 4.25 1.4167 0.68 0.3367 13.928 ST6 0.445 1.0625 2.3075 0.51 0.2525 12.947 ST7 0.356 0.85 1.846 0.408 0.202 12.33 July-August (P4) ST1 13.99 14.11 12.99 11.5 13.5 28.06 ST2 5.88 6.55 14.36 1.52 3.01 20.656 ST3 4.22 5.36 12.36 1.02 1.73 27.785 ST4 0.89 2.125 4.615 1.02 0.505 20.073 ST5 1.4067 5.36 1.7867 0.34 0.5767 14.583 ST6 1.055 1.34 3.09 0.255 0.4325 13.556 ST7 0.844 1.072 2.472 0.204 0.346 12.91 September-October (P5) ST1 13.44 12.55 11.55 13.01 12.98 24.99 ST2 3.69 2.34 11.25 3.66 0.55 18.448 ST3 3.65 3.11 15.65 2.98 0.72 24.815 ST4 1.825 1.555 7.825 1.49 0.36 18.771 ST5 1.2167 3.11 1.0367 0.9933 0.24 13.025 ST6 0.9125 0.7775 3.9125 0.745 0.18 12.107 ST7 0.73 0.622 3.13 0.596 0.144 11.53 Table 3. Monitoring stations and their coordinates. 37 Int. J. Aquat. Biol. (2023) 10(1): 34-40 samples with significant temporal and spatial variations. The average concentrations of six heavy metals, including Cu, Cd, Ni, Mn, Co, and Fe were 3.741±4.219, 3.654±4.169, 7.700±6.251, 2.551± 3.898, 2.292±3.996, and 18.236±5.583 µg/L, respectively. All the sampling sites showed an overall rising trend in the presence of heavy metals from upstream (ST7) to downstream (ST1) (Fig. 1). The first station (ST1) had the highest average concentrations of the six heavy metals of Fe, Co, Mn, Ni, Cd, and Cu, which were 25.70417, 11.73083, 11.90917, 13.15833, 12.67583, and 13.06667 µg/L, respectively. The concentrations decreased in the order of Fe > Cu > Ni > Cd > Mn > Co. There were significant differences in heavy metals abundance between sampling periods (Fig. 2). The Fe had the highest concentrations during study periods, and its concentration decreased in the Sampling Time Sampling Site Heavy metals concentration µg L-1 Cu Cd Ni Mn Co Fe November-December (P6) St1 13.22 11.5 13.33 11.22 9.56 22.55 ST2 8.11 1.16 6.22 1.23 1.33 17.856 ST3 5.36 0.65 3.17 1.09 1.03 24.018 ST4 2.68 0.325 1.585 0.545 0.515 18.168 ST5 1.7867 0.65 0.2167 0.3633 0.3433 12.607 ST6 1.34 0.1625 0.7925 0.2725 0.2575 11.718 ST7 1.072 0.13 0.634 0.218 0.206 11.16 Mean 3.741 3.654 7.700 2.551 2.292 18.236 ±SD 4.219 4.169 6.251 3.898 3.996 5.583 Table 3. Continued Figure 1. The distribution of heavy metals in the surface waters of the Shatt Al-Arab River at the study sites. Figure 2. Distribution of heavy metals in the surface water of the Shatt Al-Arab River at different times. 38 Al-Najar et al./ Short-term assessment of heavy metals in surface waters of the Shatt Al-Arab River following order: P4 > P2 > P5 > P1 > P6 > P3. While nickel was in the following order in terms of concentration: P1 > P2 > P3 > P5 > P4 > P6, as the second rank after Fe. For Cu, the highest concentration was during periods 1 and 6. The highest concentration of Cd was during periods 4 and 3 and the highest concentrations of Mn and Co were found during periods 4 and 3, respectively. Discussion A spatial and temporal distribution of the surface water temperatures of the Shatt Al-Arab River, showed typical seasonal variability, reflecting changes in air temperature and dynamics of the river flow. The pH value did not alter seasonally, but there was some spatial variability along the Shatt Al-Arab River. These values were within the range of the USEPA (1999) criterion for surface water (6.5-9). Salinity in Shatt Al-Arab is mostly caused by seawater entering the river from Iraqi marine waters. Salinity variation across seasons and sites can be correlated with flow regimes and seasonal influences (Al-Asadi et al., 2019). Chemical ions entering the river from its major tributaries and sea salt entering from the sea both impact the quality of the Shatt Al- Arab River. The mean salinity concentration is due to the loss of most tributaries of the freshwater flow in the river combined with increases in seawater intrusion from Iraqi marine waters (Moyel and Hussain, 2015; Abdullah, 2016). Thus, the mean salinity values at all studied sites along Shatt Al- Arab River were increased from Qurna (ST7) (5.31 g/L) to Fao Sea (ST1) (34 g/L). These results indicate a tendency toward water stress due to rising water demand by population growth, the development of irrigated land, the building of dams within river basins, and other factors. Reduced runoff and increased water evaporation losses have also been caused by climate change. Heavy metals are highly persistent in the environment and can be toxic for living organisms. The current study showed that trace metal concentrations are below WHO recommendations (WHO, 2011). According to the salinity, the river can be divided into two regions. These regions could also be easily recognized due to their heavy metal concentrations. Extremely low heavy metals were found in the first region, which comprised the Qurna (ST7), Harth (ST6), Sidebaed Island (ST5), and Basrah city (ST4). The second region, which includes Abu Al-Khaseeb (ST3), Fao city (ST2), and Fao Sea (ST1), had the highest concentration. Therefore, there was clear evidence that seawater intrusion influenced the levels of heavy metals. Salinity, pH, geological environment, and terrestrial runoff are a few variables that might have affected metal changes (Raknuzzaman et al., 2016). Cd, Cu, and Pb in lake water can be decreased by raising pH levels because proton binding decreases as pH rises, reducing the metal-binding capacity (Tokalioglu et al., 2000). Water volume and velocity are positively correlated with the level and distribution of heavy metals in surface water (Alloway and Steinnes, 1999). Heavy metals in the surface water were diluted by the high-water volume and velocity, decreasing their concentration. One of the factors causing a decrease in the concentrations of heavy metals in the surface water is rainwater entering the surface of the water body in a short period (Shamsuzzaman et al., 2012). The levels of heavy metals in the Shatt Al-Arab River surface waters during the summer (P3, P4, and P5) showed a slight increase compared to the rest of the year. The Shatt Al-Arab River experiences a major decrease in water volume and velocity during the dry seasons, and the physical and chemical characteristics of the water body differ noticeably from those during the rainy season. While land use patterns and levels of human activity on both banks of the Shatt Al-Arab River have remained mostly unchanged throughout this period, the residual concentration of heavy metals in the surface water has increased dramatically. Hence, to monitor and assess local ecological and environmental conditions, it is essential to know the spatial distribution of heavy metals in surface water (Mohiuddin et al., 2011). In conclusions, the primary causes of the salinity 39 Int. J. Aquat. Biol. (2023) 10(1): 34-40 of Shatt Al-Arab waters are from Marin water. This work provided baseline data on some toxic heavy metal concentrations in the surface water of this river at various times and locations following seawater intrusion. The results showed that heavy metal concentrations are below WHO recommendations. All the sampling sites showed an overall rising trend in the presence of heavy metals from upstream (ST7) to downstream (ST1). 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