Detection of contamination by some trace elements in the muscles of Carassius auratus (Linnaeus) collected from the Euphrates River / Central Iraq

The study involved measuring the concentration of seven trace elements (Cd , Pb , Zn , Fe , Mn , Se and Ni) In edible tissues of three classes of different weight and height of Carassius auratus (Linnaeus) collected from three sites of the Euphrates River, which Al- Hindiya barrage (rst site) and Touirij (second location) and the Kil (third site), for the period from Spring 2015 to Winter 2016 , and included also The study also estimated the concentrations of the trace elements studied in river water, in both dissolved and particular form , as well as exiamining of some physio- chemical properties of water river , which variations depended on the different both sites and seasons The Findings of the present study indicated seasonal changes in the concentration of trace elements studied in both water forms (dissolved and particular form) and in sh muscle in the three locations of the current study. These were noticed that the level of trace elements in the third group, the contrast of the rst and second categories was strong, and the nding found a clear link between the length and weight of the sh and the concentration of the sh as elements of concentration increases with increasing length and weight . The results founded that the concentrations of trace elements studied the particular form of higher compared to dissolved form as well as to the effective of certain physical and chemical properties of water such as Temperature, pH, Electrical conductivity and salinity on the concentration of these trace elements.


Introduction
The general problem is environmental pollution and the most important pollutants in the aquatic network are heavy metals due to their toxicity, accumulation and biomagni cation by marine creatures. Industrial, domestic, agricultural and human activity activities can typically become the source of pollution of heavy metals by natural aquatic systems (Velez & Montoro ,1998And Conacher & Mes ,1993. Pollution caused by heavy metals may have dreadful effects on the ecological equilibrium of heavy metal pollution and a number of aquatic entities (Akinmoladun , et.al.,2007And Vosylien & JankaitÄ , 2006. In the food chain, toxins such as heavy metals bioaccumulate and cause adverse effects, even death, so sh are used to assess the health status of the aquatic environment among other species (Farkas & Salanki , 2002And Al-Yousuf & El-Shahawi, 1999. Heavy metals in sh come predominantly from their diet, and contaminant bioaccumulation levels are higher in sh that are higher in the food chain (EFSA,2005) Heavy metals penetrate sh bodies in three possible ways: through gills, through the digestive tract, and through the surface of the body. The gills are regarded as the critical site of direct absorption of water metals (Romeo ,et.al.,1999And Beijer & Jernelov ,1986. Affected organisms show response to heavy metals by accumulating them in their bodies or by transferring to the next trophic level of the food chain (Shah and Altindag ,2005). Fishes aregood Indicators of contamination of trace metals and the possible risk of human use (Papagiannis,et.al., 2004).The adverse effects of these contaminants can and can not avoid Olaifa,et.al.,2004).
As they reach a high trophic level and are an signi cant source of balanced protein in the human diet, sh are also seen as a signi cant bioindicator of the aquatic environment. Due to their value in the human diet, sh must be carefully screened to ensure that the intake of sh does not transfer harmful amounts of heavy metals to the human population (Rahman, et.al.,2012). Monitoring the contamination of heavy metals in river systems by the use of sh tissues helps determine the quality of aquatic environments (Adam, 2002).In this context, sh samples are considered one of the most signi cant variables in estimating the contamination of trace metals in freshwater systems. (Cinier, et.al.,1999 ;Has-Schön, et.al.,2006 andRashed, 2001). In this context, sh samples are considered one of the most signi cant variables in estimating the contamination of trace metals in freshwater systems. ( Canli, et.al., 1998 ;Yilmaz, 2003 andHenry, et.al., 2004), Each species of sh has a speci c way of accumulating (and/or removing) metal when exposed to such contaminants Peakall, & Burger,2003). Fish in the upper food web role, on the other hand, are likely to accumulate metals and cause human contamination through foods that cause chronic and acute diseases. (Has-Schön, et.al.,2006And Al-Yousuf, et.al.,2000. The level of trace metals in various sh organs is used as an ecosystem metal contamination index, which is considered to be an important instrument to highlight the role of elevated metal levels in aquatic species. ( Tarrio, et.al.,1991). Metal concentrations are harmful to sh if their level reaches the acceptable level. (Mansour and Sidky , 2002).
The aim of This research was intended to determine the concentrations of heavy metals(Pb , Cd, Se, Ni , Fe, Mn, Zn) Three distinct weight and length types in water and muscle of Carassius auratus (Linnaeus) collected from three sites of the Euphrates River , Since this sh is an essential component of this zone's human diet. The ndings of this analysis will include details on the background levels of metals in water and sh species, contributing to The successful monitoring of both the quality of the atmosphere and the health of the inhabiting species the River ecosystem.

Materials And Methods
Gold carp samples were collected Carassius auratus (Linnaeus) and water is seasonal from three locations on the Euphrates River, which is the Al-Hindiya barrage ( rst site) and Touirij (second location) and the Ki l ( Figure 1) . The collected sh samples were divided into three longitudinal and weight categories.
The samples were collected for the period 2015-2016, and the water samples were taken from the middle of the river Using clean polyethylene bottles washed with acid and distilled water distilled for the purpose of examining some physical and chemical properties and to measure the concentrations of some trace elements in water.
Carassius auratus (Linnaeus) belongs to the Cyprinoidae family and is considered one of the shes that have a great economic value in Iraqi waters, and Al-Daham, 1977). indicated that this type of sh is frequently found in the central and southern sections of Iraq, and carp is considered one of the most resistant to environmental conditions. Di culty In addition to having a good sexual growth and maturity Jeney and Jeney ,1995).
Certain physical and chemical properties of the collected water samples from the river water which were related to its effect on the concentrations of trace elements were increased or decreased which are the water temperature, the electrical conductivity EC, and the pH of the river water. Amount of DO, and total dissolved solids T.D.S. Total solids suspended from T.S.S., in addition to salinity. The concentration of dissolved trace elements in river water was calculated using the method described by (Riley, and Taylor, 1968).
As for the trace elements in the particulate phase, it followed the method (Sturgeon, 1982).The sample of each of the classes of the Carassius auratus (Linnaeus) grouped and divided according to weight and length according to (R.O.P.M.E., 1982). was digested after the muscle tissue was separated from the bone and severed and well mixed and dried with an oven at a temperature of (70) degrees Celsius, then all samples were measured using an Atomic device Absorption spectrophotometer-Model (5000) Statistical Analysis: All of the data was expressed as ±SD. For mean separation, the minimum signi cant difference (LSD) was used. The signi cant level was set at the likelihood level of P<0.05.

Results And Discussion
The rapid growth of industry and agriculture has resulted in increased emissions of heavy metals in recent decades, which poses a major environmental risk to invertebrates, sh and humans(] Uluturhan And kucuksezginf , 2007). Heavy metals should be highlighted among the pollutants, because of the effects of their bioaccumulation in marine environments. ( Nadmitov ,et.al.,2015 andSlomanka, 2007). Signi cant amounts of these metals are released into waterways where they can be highly deposited and biomagni ed in the water , soil and aquatic food chain, resulting in both sub-lethal effects and deaths in local sh populations. ( Megeerj, et.al.,2000 ;Xu Yj, et.al.,2004 andJasim, et.al.,2014).
Table (1) shows the ranges of lengths and weights of the golden carp sh Carassius auratus (Linnaeus) grouped from three study sites located on the Euphrates for the period 2015-2016, while Table (2) shows the difference in the seasonal values of some characteristics The physical and chemical properties of the Euphrates River in the study sites. Table (3) shows the seasonal concentrations of the studied heavy elements (Cd, Pb, Zn, Fe, Mn, Se and Ni) in the soluble and particulate form of the Euphrates water in the studied sites and the Table (4) shows the seasonal concentrations of the seven heavy elements studied In the muscles of the three classes of Carassius auratus (Linnaeus).
The results of the current study found the annual rates of heavy metals concentrations in the waters of the river as dissolved form were The order of has been taken as follows: While The concentrations of these elements in water as particular form have taken the following order: Iron> Zinc> Manganese> Cadmium> Lead> Nickel> Selenium.
Heavy elements in the water as a particular form in the present study had higher concentrations compared with the dissolved form and this is attributed to the process of adsorption, as these elements tend to linkage on the surfaces of some materials, especially particulate matter and organic mud that spreading in the water column (Demina , et.al.,2009 andDhurgham, 2018).
The results of the current study stated that there is a quarterly variation in the concentrations of the studied elements, the highest concentrations was recorded in summer, while lowest concentrations were in winter and for both forms dissolved and particular due to the large number of pollutant sources and to the difference in capacity of the river to receive different amounts of discharged substances, As that Discharges from domestic, manufacturing and other manmade activities have contributed to high levels of concentrations of heavy metals in freshwater. ( Vinodhini and Narayanan ,2008).
in addition to the difference in temperature between seasons, which affects directly and indirectly on the concentration of trace elements in water , or may be due to differences in the values of both pH and the values of salinity and water hardness in addition to the difference in the amount of total dissolved substances, as well as total suspended materials that directly affects the readiness of the elements for living organisms (Kumar andAchyuthan ,2007 And Dhurgham, 2014).
Mitigating factor may play the primary role in in uencing the concentration of elements in addition to the change in the water level of river, and may be the life activities for some organisms also play a role in in uencing the concentration of these elements, which in turn is affected by many factors including the amount of food, reproduction and the length of the lighting (Salman , 2011). Also, as a result of the study, the low concentrations of some elements in some seasons, is because of the ability of these elements to accumulate in the bodies of living organisms, or to be removed continuously by removal process or by the linkage with through the process of adsorption on some suspended Substances materials and therefore deposition (Dhurgham, et.al., 2014).
The relationship between some physical and chemical properties of water with a concentration of heavy metals dissolved and particulate matter shown by the results of statistical analysis, it was found that there is a direct signi cant correlation relationship between the concentration of heavy studied elements in the water of the river and the temperature, as it increases the concentration in hot seasons because of the high temperature (Abd and Musa ,2009) . the cause of the low concentration of elements in the spring is due to that this season is the growing season and thus the plants absorb the bulk of these elements in this season because they are necessary to complete the biological processes, while in the summer, the concentration of these elements increase due to several reasons, mainly because of the high temperature and thereby increase the evaporation rates as well as increased degradation of the dead organisms which leads to lack of absorption of these elements by the living organisms. Bacteria, especially, anaerobic sulfur bacteria a key role in the reduction of most of these elements as the heavy elements mixed with organic materials through analysis by bacteria (Park, et.al., 2008).
The results of the present study showed that the concentration of heavy elements in the waters of the river both in dissolved and particular form affected by the values of pH, as the results of statistical analysis shown there is a reverse correlation between them, as the pH of water affect the solubility of heavy metals by increasing the amount of adsorbed elements on organic matter by the increase of the pH values and thus lead to the deposition (Odum, 2000).
while the decrease in the pH values will lead to increase competition between the elements ions and hydrogen ion to link to active sites, also it's working to dissolve the complex (carbonate/ elements), leading to release the items to the water column (Forstner & Wittmann, 1981).
The electrical conductivity and salinity have been found by the results of statistical analysis that there is a signi cant reverse between them and the concentration of studied heavy elements as they affect the process of absorption and adsorption of these elements in organic matter (Kathikeyani , et.al., 2002).
Found by the results of statistical analysis of the current study that the amount of total suspended Substances associated closely to the concentration of river water as particular form due to the abundance of phytoplankton in the Euphrates River , as the plankton concentrate large amounts of heavy elements in the water through absorption (Dhurgham , et.al., 2014).
The results of the present study showed that the annual mean concentration of the studied heavy metals (Cd, Pb, Zn, Fe, Mn, Se, Ni) in the muscles of the rst category, second and third of the Gold carp sh Carassius auratus (Linnaeus) The arrangement in the muscles of the three groups in the studied sites is as follows Zinc> Iron> Nickel> Manganese> Selenium> Lead> Cadmium.
The current study showed that the third category of sh Carassius auratus (Linnaeus) contained the highest concentrations of heavy elements than for rst and second category, and this may be because the increase of concentration of the element by the increase of the size and length of sh  and ] Blasco , et.al.,1998).
That the concentration of Zinc element, as is evident from the results was high compared to other elements and the reason This component is important for preserving the gonads and protecting the marine ecosystem from the effects of cadmium toxicity, and this purposely shes to consume large quantities of this component. Hammoud, et.al.,2005).
Add to that the study showed that In the muscles of the three types of sh studied, the concentration of the selenium element was high and there was proof of the absorption of that element from water into the bodies of living organisms , including sh, and this is strong evidence on the basis of sh as a critical indicator for suggesting the existence of pollution of these dangerous heavy elements (Benson , et.al., 2007).
The relationship between the concentrations of heavy metals studied in the muscles of Carassius auratus (Linnaeus) with some studied physical and chemical properties, they found a direct signi cant correlation relationship between temperature and the amount of heavy elements, with the highest concentration of these elements in sh muscle was in summer, spring and attributed the reason to increase the accumulation of heavy elements in the warm seasons compared to the cold seasons, as the high temperature causes an increase of metabolic events and the high level of metabolism and thereby increase the concentration of heavy elements within the body of sh (Zayed , et.al.,1994).
In fresh water, heavy metals accumulate and grow through the food chain. The bioaccumulation patterns of heavy metals are calculated by sh absorbance and excretion rates. Different variables such as water's physical and chemical properties as well as seasonal changes are the explanation for substantial metal augmentation in various sh tissues. (Romeo , et.al., 1999). Stern metal residual problems in the sh epithelium are due to the presence of higher concentrations of metal in water and (Wong , et.al., 2001).
Conclusions 1 -The concentration of heavy elements in the waters of the Euphrates River as particular form was higher as compared to dissolved due to the adsorption of elements on the suspended Substances in the water.
2 -The quarterly variation in the concentrations of heavy metals studied in both in water as dissolved and particular in the muscles of Gold carp sh Carassius auratus (Linnaeus). It was high in summer compared to winter.
3 -Third longitudinal and weighing category recorded Gold carp sh Carassius auratus (Linnaeus) high concentrations of heavy studied elements, and higher than the rst and the second categories, due to the difference in the speed of growth in addition to the length of exposure.
4 -A signi cant positive correlation recorded between the concentrations of heavy studied metals in water (dissolved and particular) and in sh muscle with temperature, while a reverse signi cant correlation was found between the concentration of elements in the water with the pH, salinity and electrical conductivity.
5 -A signi cant direct relationship correlation between the concentrations of seven studied elements in the waters of the Euphrates River as particular with the amount of total suspended Substances.