Monitoring Pollution of the Tigris River in Baghdad by Studying Physico-Chemical Characteristics


 The current study aimed at exploring and identifying pollution indicators of the Tigris River in Baghdad through studying physical and chemical characteristics. Monthly water samples were collected from four locations along the Tigris River in Baghdad for 12 months period. The studied characteristics of the current study included surface water temperature, pH, turbidity, salinity, electrical conductivity, total suspended solids, total dissolved solids, total hardness, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, phosphate, nitrate, and Sulphate. The results showed that the mean values of all the studied physical and chemical characteristics except pH, temperature, and phosphate were higher than the acceptable limits of the Iraqi river water guidelines and international standards. The current study concluded that the Tigris River water was heavily polluted from untreated sewage discharge and other industrial, agricultural, and domestic activities. The study recommended immediate measures to be taken to end the nonstop inflow of sewage and wastes into the Tigris River water from the residential, commercial, and institutional activities in Baghdad.


Introduction
Pollution levels in the Tigris River in Iraq are on the increase. The river pollution has a serious negative effect on humans, animals, and the way of life. Consequences of such pollution has led to the bioaccumulation of heavy metals in freshwater shes ( Physical characteristics such as water temperature, turbidity, and total hardness of the river water can be good indicators for determining pollution. Similarly, chemical characteristics (electrical conductivity, pH, concentrations of K + , Na + , Cl, and NO 3 etc.) represent key parameters in monitoring and identifying pollution in river water (Chapman, 2003). Microbiological contamination is also an important factor with regard to the treatment requirements and safe recycle of e uents of river waters (Basílico, de Cabo, and Faggi, 2015).
Most of the domestic and industrial wastes are discharged directly into the Tigris River in Baghdad without any su cient waste management, which makes the Tigris River water severely polluted specially with organic substances. Quality of the Tigris river water in Baghdad was classi ed as "very poor" (Khudair, 2013). A more recent study classi ed the Tigris River as "fair quality" (Ibrahim, Abd Ali, and Hussein, 2018). With the upsurge of industrial activities and the increased anthropogenic processes due to the rise of population in Baghdad, the Tigris River would be more exposed to pollution with e uents and wastes. In the end, this would lead to a serious public health problem in addition to the severe consequences on the environment.
The Tigris River is the only source for potable water supplies, sh consumption and farming, agricultural water supply, and also used for navigation, recreation, and industries in Baghdad. Hence, and according to the recommendations of the World Health Organization (WHO, 2002), it's very important to keep monitoring and evaluating the river water quality by conducting frequent ecological, biological, and physico-chemical assessments and examination of water supplies. This would involve monitoring at all times, from a public health perspective, over safety and sustainability of water supplies (Okorafor et al, 2012).
The aim of the current study is to monitor pollution of the Tigris River through exploring and identifying some physical and chemical characteristics of the Tigris river water within the city of Baghdad.
Monitoring and evaluating physico-chemical characteristics in the river water will help identify the impact of pollutants on the water quality of the Tigris River. Consequently, a better intervention and solution by the relevant authorities would be taken to help mitigate the problem of Tigris River pollution in Iraq.
2 Materials And Methods:

Study Area:
Four sampling locations were selected for the current study. Al-Rashdiya area was the labeled as sampling station. This area is located northern of Baghdad and it marks the entrance of the Tigris River to the city of Baghdad. It is located at the following GPS coordinates (Latitude 33°25'42.0"N and Longitude 44°20'47.7"E). Bab Al-Muwadam labeled as sampling station 2 and it is located at the following GPS coordinates (Latitude 33°20′37″ N and longitude 44°22′48″ E) in central Baghdad and the third sampling location was the industrial area at Al-Zafaraniya labeled as sampling station 3 and it is located at the following GPS coordinates (latitude 33°17'22.7"N and Longitude 44°27'01.8"E) in the south of Baghdad. The last sampling station was the part of the Tigris River where it merges with the Diyala River southern Baghdad and it is located at the following GPS coordinates (Latitude 33°13'15.9"N and Longitude 44°30'20.9"E). Reasons for selecting those four locations come from the recent and previous o cial reports and academic studies showing the increase of pollution in these areas (Mensoor and Said, 2018; Al-Obaidy, Al-Janabi, & Shakir, 2015; Ishnawa, Fari, and Sadeq, 2009). Station 2 and 3 were common locations for discharging domestic wastes, e uents from medical and industrial compounds located nearby in addition to the release of municipal wastes. While station 1 and 4 were selected as they represent upstream and downstream of sewage disposal sites. This way, the four selected sampling stations can provide better information and data about the river quality.

Collection of Samples:
Surface water samples from the Tigris River were randomly collected from two different sites for each of the four selected sampling locations. Each sample was labeled with the date of collection and the site of sampling. Collection of the samples was done through wading the surface river water at both sampling stations. The river water samples were collected in clean and sterile polyethylene bottles every month during the study period from December 2018 to November 2019. 24 water samples for each site were taken (96 samples in total). The samples were taken immediately after collection from the locations to the laboratory for analysis of physical-chemical parameters.

Physical and chemical characteristics:
The temperature of the water was measured at the sampling locations with a handheld portable thermometer (The Waterproof Thermistor Thermometer -HI93510, U.S.A). A pH meter (HI98108 pHep, U.S.A) was used and it was measured on site. For electrical conductivity (EC), a handheld portable meter 3 Results And Discussion: The results of physico-chemical analysis are presented in Table 1. The Tigris River water temperature varied among the 12 months period. But, the values of temperature degrees for the four sampling locations ranged between 11.1 and 30.7. The temperature of the ambient air in uenced the variance in water temperature during the 12 months period. The mean values showed that they are within the acceptable range of water temperature of surface river water. Under natural conditions, the temperature of rivers' water varies between 0°C and 30°C (Chapman, 2003).  . This alkalinity of the Tigris River surface water could be attributed to the increased disposal of domestic wastes into the river water at different sites along the Tigris river in Baghdad.
Electrical conductivity (EC) of river water represents a function of the concentration of ions in a solution, the nature of dissolved substance, and the temperature (Tolgyessy, 1993 Water hardness is resulted from the presence of calcium (Ca) and magnesium (Mg) compounds, and by different other metals. Hard water does not pose a danger to the public health, but economically it represents one of the most critical water quality parameters (Berthouex and Brown, 2018). In fact, hard water helps teeth and bones grow; and lowers toxicity to lead poisoning from lead pipelines. On the other hand, soft waters are believed to be associated with cardiovascular diseases (Spellman, 2003 However, the current study showed higher results of water hardness than any other former study. Values of total dissolved solids (TDS) for sampling station 1 ranged from 569 to 804 mg\L and for the second sampling station were (550.5-804 mg/L). While sampling station 3 and 4 had values ranging between (755 to 1303 mg/L). These values were within the WHO acceptable limits of total dissolved solids in river waters (1000 mg\L). However, the increased values could be attributed to higher concentrations of discharged e uents nearby the sampling stations since the four sampling locations are considered heavily populated and industrialized areas. These results are higher than the results obtained by some previous studies that indicated the Tigris River is characterized with increased values of TDS and that the river water is more saline in the central and southern areas of Iraq (Al-Shujairi, Sulaiman, and Najemaldin, 2015; Ali and Shaban, 2014). Moreover, high concentrations of TDS are common in freshwaters in arid climates, as the case in Iraq, which is considered an arid region (Boyd, 2015). Al-Saady and Abdullah (2014) indicated that the registered increased TDS values along the Tigris river in Baghdad and the southern areas resulted from several factors such as: the agricultural lands along the Tigris river that are characterized with high salt content. In addition, there is a noticeable reduction in levels of the Tigris river water in Baghdad. Moreover, the high evaporation of river water that lead to increasing salt in river water. It's noteworthy that the increase of TDS downstream the Tigris River is resulted from the extensive agricultural activities in the area between Baghdad and Umara city.
However, runoff and return ow from agricultural land that contain fertilizers can also lead to high TDS value (Saady and Abdullah, 2014).
Total suspended solids (TSS) represent a measure of the weight of relatively insoluble materials in the ambient water. Suspended solids can include both organic (detritus and biosolids) and inorganic (sand or ner colloids) constituents (Spellman, 2003). The WHO does not have a limit for TSS, but the European Union set (25 mg/L) as a limit for sheries and aquatic life in rivers (Chapman, 2003). TSS values for the 1st sampling station ranged between (35.5-99.2 mg/L). TSS values for the 2nd station were (40.2-140.8 mg/L). While TSS values for the third and fourth sampling stations ranged between (44.2 to 141.9 mg/L).
The current high TSS results shown in this study come in consistence with the ones obtained by (Alhassany & Al-Bayyati, 2017; Matti, 2014). Though, the current study had much higher results than the previous studies.
Dissolved oxygen is a very important water characteristic. DO is necessary to preserve most forms of aquatic life and to allow the decomposition of organic matter, including organic wastes (Nesaratnam, 2014). The current study showed the average value of dissolved oxygen (DO) in the Tigris river water was ranging from (6.8 mg/L to 6.8 mg/L) at all the four sampled stations. These values are acceptable according to the Iraqi and international standards where DO values must not be less than 4 mg/L. The current results agree with previous studies con rming that the dissolved oxygen levels in the Tigris River water are within the acceptable international standards (Matti, 2014; Al-Bayatti, Al-Arajy, and Al-Nuaemy, 2012).
Biochemical Oxygen Demand (BOD) is the amount of oxygen microorganisms use to decompose organic wastes that are present in water (Carmen, 2009). BOD is a very commonly used environmental test and considered as the most important marker of river water organic pollution (Nesaratnam, 2014). BOD values ranged between (3.5-5.9 mg/L) at sampling station 1 and (5.5-6.9 mg/L) at the second sampling station. While sampling station 3 and 4 registered BOD values ranging between (5.5-6.9 mg/L). The increased BOD range detected at the four sampling stations exceeds the international standards for BOD levels in river waters (<5 mg/L). The current results are much higher than the ones obtained by Nitrogen is present in the river water in the form of nitrate (NO 3 ). Presence of Nitrate in the water indicates that the river is polluted with sewage. Nitrate in river water can be a serious public health danger to both human and animal infants. High concentrations of nitrate in drinking water can even cause death (Drinan & Spellman, 2001). Agricultural activities are considered the main source of nitrate pollution (Singh, & Tripathi, 2007). Values of nitrate detected at the 1st sampling station ranged from (3.6-11.3 mg/L) and Previous studies did not register such higher values in that location. This shows that the sampling station 4 is being polluted heavily over the past few years.
There are two forms of sulfur (S) common in water and wastewater: sulfate (SO 4 2− ) and hydrogen sul de (H 2 S). Sulphate (SO 4 2− ) in high concentrations can cause a laxative effect and a bitter taste and is considered a nuisance in drinking water (Berthouex and Brown, 2018 the Tigris River water pollution mainly come from the continuous industrial in uents that are discharged into the river without prior treatment. This will lead to the deterioration of the Tigris River water quality and increased levels of pollution with different chemicals. The current study indicated that the primary source of the Tigris River water pollution comes from sewage e uents that are directly discharged into the river water without proper treatment. Previous studies (Al-Ansari, Ali & Knutsson, 2015;Hamza, 2007) showed the current waste management methods applied in Iraq need further investigation and review to better handle the increasing pollution levels coming from the sewage. The consequences of such pollution would include the Tigris River water quality impairment, drop in sh abundance, and will have a severe effect on water usage for recreation (swimming, wading, and boating), industrial, and domestic purposes. The increased municipal and agricultural wastes that are directly discharged into the Tigris River water without proper treatment remain a major environmental challenge and a public health threat to the Tigris River water. In general, the Tigris River water quality is poor and this result is consistent with the ndings of previous studies con rming the deterioration of the Tigris River water quality in Iraq

Recommendations:
Immediate measures are required to be taken to end the nonstop in ow of sewage and wastes into the Tigris River water from the residential, commercial, and institutional activities in Baghdad. It's very important to call for speeding up drafting local environmental legislations and laws in Iraq as soon as possible. Rehabilitating and renovating waste management methods adopted by the local authorities is a key step towards improving water quality in Iraq. Moreover, further detailed studies covering more sampling stations along the Tigris River in Iraq should be conducted so that we can better compare results. Finally, a nation-wide media campaign would be necessary to help educate o cials and citizens about the public health, environmental, and economic dangers of the Tigris River pollution in Iraq.