A SIAN J OURNAL OF C HEMISTRY A SIAN J OURNAL OF C HEMISTRY Seasonal Variation in Heavy Metals Contamination in Surface Water of Shatt Al-Hilla River, Babylon, Iraq

variations in the concentration of heavy metals (Pb, Ni and Fe) in Shatt Al-Hilla river water have been carried out during November 2011-October 2012 to study the extent of contamination of the river with these metals. Sampling was achieved from 14 selected study sites (most likely to be affected by pollutants). The technique of flame atomic absorption spectrometry was used to determine the concentration of heavy metals in the water samples. Results have shown wide variations in the heavy metals levels varying from high concentration of one of the metals at certain site to low content of other. A total of 168 surface water samples collected from Shatt Al-Hilla river in med of Iraq, were analyzed for Pb, Ni and Fe. The concentrations of the metals Pb, Ni and fewere detected in 100 % of the samples in the range of 0.030-16.090, 0.080-13.000 and 0.040-8.110, respectively.

children 27,28 . The rank of Pb is the second in top twenty lists of the most poisoning heavy metals (after arsenic), its target organs are the bones, blood, kidneys, reproductive and cardiovascular systems, brain and thyroid gland 29,30 . The main target organs for Cd are the kidneys and liver 31,32 . Exposure to high levels of Zn may cause muscle pain, acute renal failure, pancreatitis, anemia and death. The main target organs of Feare the kidneys, cardiovascular system and liver 33 . Certain human illness is related to Cr consumption such as allergic skin reaction, chronic ulceration and perforation of the nasal septum 34 . Over exposure to Ni cancause heart and liver damage, decreased body weight and skin irritation 27 . Therefore monitoring these metals is very important for safety assessment of the environment and human health especially.
In Iraq and particularly in Al-Hilla city, urban agriculture has been a normal practice along both river banks. Previous studies were reported that the pollution existed by toxic chemicals and heavy metals from industries which discharge waste water untreated into river stream directly, discharge of effluents from domestic and municipal sewage, agricultural activation, oil and lubricant and car washing. For these reasons, this work objective to monitor the river water over long period of time in order to describe average metal contamination and its trend, which is essential component of any pollution control management.

Description of study area:
The Shatt Al-Hilla river is one of the most important rivers for water supply and irrigation in the Babylon Governorate. The total length of this river is 97 km. Many pollution sources are present near this river such as draining sewage, agriculture pumps and textile factories treated wastewater. The Shatt AL-Hilla river starts from Saddat Al-Hindya and finishes on the southern borders of Al-Hilla city in Sadder Al-Dughara, passing through several villages and cities. These sites were selected during a boat trip to explore the sites contaminated. Study area was described in previous work 35 .
Sampling and collection of water samples: A total of 168 water samples were collected along Shatt Al-Hilla from fourteen sampling point between Novembr-2011 and October-2012. Water samples were collected from a depth of 1ft below the surface using polyethylene containers 1 L. The containers are washed well with detergent then with distilled water and soaked in 10 % nitric acid then washed water sample twice and finally filled with the water sample and 2 mL of concentrated HNO 3 is added and the container is capped sealed and sent to the laboratory where the sample is filtered by passing through 0.45 µm membrane filter 36 .
Analytical methods: The heavy metals were analyzed by using GBC scientific equipment flame atomic absorption spectrophotometer by applying the following parameters in triplicate analysis: Table-1, illustrate the parameters were applied for all samples. All chemicals were used for preparation of standard solution for the calibration curve is of analar grade chemicals. 150 mL of sample was transferred to a beaker (250 mL), 5 mL of concentrated nitric acid was added and the mixture evaporated to dryness on a hot plate. (1-2) mL of concentrated nitric acid was added to dissolve all the residues on the walls of the beaker. The distilled, digested samples were filtered and made more than 50 mL and analyzed by atomic absorption spectrometer (AAS). The blank was prepared by carrying distilled deionized water for all the above procedure 37,38 .

RESULTS AND DISCUSSION
The results of the determination are presented in Tables  2-4 Table-2. The mean concentration of lead in water was found extremely higher than the permissible limit for lead in drinking water which is less than 0.05 ppm according to WHO 39 . The highest concentration of lead may be attributing to the accumulation effect for the previous sites which they locate before this site, by moving with water stream to be at highest value in this location especially if we take in consideration that is in this location no pollution source. The factories which located in study area such as Al-Sadda cement factory and Al-Furat establishment for chemical production may be contribute to elevate the heavy metals levels generally and lead specially in study area. Standards which is very dangerous as lead poising causes gastrointestinal, neuromuscular and central nervous system disorders and also cause liver and kidney damage, reduced hemoglobin formation and infertility and birth defects. The high concentration of lead in the river can be related to the discharge in the surface water through paints, solders, pipes, building materials and combustion of oil and gasoline which accounts for more than 50 % of all anthropogenic emmitions and the atmospheric fallout is usually the most important source of lead in fresh water 40 Table-3. The presence of high concentration of nickel in Shatt Al-Hilla river is observed as the mean concentration is greater than the permitted limit which is 0.02 ppm and this causes nickel toxicity with the symptoms of skin rash, giddiness, diarrhea and also can lead to swelling of brain and liver, degeneration of liver, irritation to the eyes, throat and nose and various types of cancer. The nickel toxicity sources are hydrogenated oils, electroplating, industries dealing with electrical equipment and house hold appliances, catalysts, pigments, batteries Ni-Cd and coal and oil combustion are the major source of nickel concentration in the water bodies. The maximum value of nickel was recorded in site thirteen, the pollution source for this site is existence of filtration station for drinking water and this station is use the pipe out let from the precipitating tanks to remove all the sediments and precipitants which remove from these tanks to river. Heavy metals in nature tend to be down in these tank, therefore when the precipitants are removed they going in high percentage at the removing time.
Iron concentrations were found to be high at certain sites in one month and differs greatly in other time also there is differences between the different sites values. The maximum value of Fe concentration gained was 8.11 ppm at site 10 in  Table-4. The observed experimental value of iron mean concentration in water was very much higher than the permissible limit of iron which 0.3 ppm when the presence of high concentration of Iron may increase the hazards of pathogenic organisms since they need Iron for their growth 40 and also causes nausea, vomiting, brain hemorrhage, anxiety, tension, cardiac arrest and metabolic disorder. The higher concentration levels of iron may be it is seeped through contaminated soil and entered the river along with the rain water run-off. The maximum value of iron was in site ten, in this site which the boats are spread using different types of fuels for their engines. The main product for iron oxide is that the flout bodies made of iron as a result of corrosion and also that produce from these engine which contribute to raise the iron levels in this site.

Conclusion
In conclusion Pb, Ni and Fe have shown elevated levels of heavy metals at many sites along Shatt Al-Hilla river in different seasons of the study. The increased levels of heavy metals in the water lead to accumulation of them in the agricultural soils and plants grown on the contaminated soils leading to great harm to humans and animals. Hence, it is obligatory to rectify the various heavy metals resources which lead to addition of these metals into the river. Also, water should be tested systematically and regularly to keep monitoring process on the heavy metals pollutant into the water and purify the water, if necessary. Further, as the heavy metals enter the food chain and get accumulated at each level from producers to consumers the heavy metal concentrations in soil and in various crops grown in the area is to be examined in addition to the river sediments which affected the aquatic life in the river.