International Journal of Marine Science, 2017, Vol.7, No.35, 353-360
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biomagnificated through the food chain and are not degradable by decomposers organisms (Al-Hejuje, 1997).
In future to protect water bodies from pollution, continuous monitoring is necessary to avoid further pollution. For
water bodies it is necessary to find out some pollution monitoring tools (Chougule et al., 2009; Yankey et al., 2013).
Heavy metal pollution indices are a useful and a relatively easy way to assess the composite of overall heavy metal
pollution (Al-Hejuje, 2014). Several methods have been previously proposed such HPI: heavy metals pollution
index (Mohan et al., 1996), MPI: metal pollution index (Meybeck
et al., 2004), and HEI: heavy metal evaluation
index (Bhuiyan et al., 2010) to calculate the overall water pollution with heavy metals. The heavy metal pollution
index (HPI) is a method of rating that shows the composite influence of individual heavy metal on the overall
quality of water (Reza and Singh, 2010; Balakrishnan and Ramu, 2016).
The main goal of the present study is to determine the temporal and spatial variations of heavy metals at the Shatt
Al-Arab River, and also apply HPI as an effective tool to assess the water pollution with heavy metals and it's
suitability for different purposes. HPI describes as a bridge between professionals and laymen or the decision
makers.
1 Materials and Methods
Water sample (5 L) were collected from each of five stations along the middle part of Shatt Al-Arab river,
Southern of Iraq during Dec., 2012 -Nov., 2013 period at the following coordinates: 30.36 623 N and 47.45 662 E
(station 1); 30.34 915 N and 47.46 368 E (station 2); 30.33 755 N and 47.47 563 E (station 3); 30.30 376 N and
47.51 328 E (station 4); and 30.27 251 N and 48.02 810 E (station 5). Water samples were collected at least 20 -30
cm under the water surface at the middle of the river using polyethylene bottles and preserved cooling until reach
the lab.
In the laboratory, water samples (5 L) were filtered as soon as possible through pre-washed (HCl 0.5 N) and
pre-weighted Millipore membrane filters (0.45 µm pore size). The filtrate was considered as dissolved phase,
while those retained on the surface of filters were considered as particulate phase. The filtrate was then
pre-concentrated using chelating ion exchange resin (Purolite-C-100 resin in hydrogen form); about 5 L of filtrate
was pass through activated ion exchange column with a flow rate of about 8 ml/min. The column was then washed
with 100 ml of deionized water and the bounded heavy metals were eluted using 50 mL of HNO
3
(2 N). The elutes
were collected in 100 ml clean Polyethylene Tri Fluro Ethane (PTFE) containers ,allowed on hot plate at 70°C
until the sample volume reduced below 25 ml. The sample volume was up to 25 mL mark with deionized water
and stored in tightly stopper polyethylene vials ready for analysis of the metals using flame atomic absorption
spectrophotometer (FAAS).
The filters were dried in oven at 60°C to constant weights and their weights recorded to obtain the values of the
total suspended matter. The exchangeable heavy metals were extracted using 30 ml HCl (0.5 N) overnight in an
orbital shaker with 300 rpm. The solution was centrifuged at 5000 rpm for 20 minute, then the supernatant was
filtered using pre-cleaned filter paper (Watman No. 1) to remove some of the suspended matters. The filtrate was
decanted and stored in tightly stopper polyethylene vials to be ready for analysis (Chester and Voutsinou, 1981).
The metals in residual phase of the particulate matter was extracted according to Sturgeon, et al. (1982), where the
above mentioned steps was washed by 40 mL deionized water, centrifuge for 20 minutes. Then samples were
digested with 5 mL concentrated HNO
3
acid in PTFE vessels at 70°C on hot plate near dryness state. The
digestion was further proceeded with 1:1 mixture of concentrated HClO
4
and HF acids. The residue was dissolved
in 30 mL of HCl (0.5 N), allowed on hot plate at 70°C, then made up to 30 mL with deionized water ,and filtered
using pre-cleaned
filter paper (Watman No. 1). The samples were stored in tightly stopper polyethylene vials to be
ready for analysis by FAAS.
1.1 Heavy metal pollution index (HPI)
The Heavy Metal Pollution Index (HPI) is a method of rating that shows the composite influence of individual
