مطالعه غلظت فلزات سنگین در رسوب و پساب اطراف رودخانه تمبی در مسجدسلیمان، خوزستان

Abstract
This study was carried out to investigate the concentration of heavy metals of Ni, Cd, Pb, As, Fe, Cr in municipal sewage discharge, urban wastewater and industrial effluent are pumped to the Tembi River. Sampling carried from 10 water and wastewater and 10 sediments. The results of ICP-MMS analysis showed the mean concentration (in ppm) for water sample for As 1/23, Zn 17/71, Cr 0/8, Ni 1.11, Cd 0.09, Pb 6/35, Fe 132/50 and mean concentration of heavy metals in sediment sample for As 0.91, Zn 23/96, Cr 91/50, Ni 56/10, Cd 0/16, Pb 10/40, Fe 14950. Based on the results obtained from the index of enrichment factor, Ni and Cr concentration showed the medium to high pollution level. Based on the molar accumulation land index, Ni and Zn concentration were in the range of moderate to high levels of pollution, and is highly contaminated in all areas with high Fe concentrations. Based on the pollution load factor sediment, It is contaminated with Ni, Cd, Fe and Cr. Based on contamination coefficient at point SA-02 the concentration of Pb and Zn in the sediment is high and As is also contaminated in site C and Ni, Cd, Fe and Cr concentration is high and the sediment is contaminated but there is no heavy metal contamination elsewhere. Tembi River receives untreated municipal and industrial wastewater. According to the results obtained, the Tembi River is in a danger and unsafe area for fishing and swimming purposes.

Introduction
Rivers are one of the most important fresh water resources for daily and irrigation purposes. The pollution of these valuable resources has caused great concern. One of the pollutants that can endanger the environment of each river is metals and metalloid.
Tembi River is one of the main rivers in masjed soleiman city , located in the east of khuzestan province, passing through the southwest of masjed soleiman city sewage system , is the waste of traditional slaughterhouse in city and surrounding villages and industrial effluents from the river course that without treatment to the river. In this research, the water and sediments were geochemically studied in terms of heavy metal pollution in water and sediments.

Methodology
Twenty samples including 10 water samples and 10 sediments samples were taken for investigation of heavy metal pollution. The sampling points were first registered using Global Positioning System (GPS) and are reported in Universal Transverse Mercator (UTM) coordinates. One sample was collected per sampling location and placed in high density polypropylene bottles previously washed with nitric acid and distilled water and washed twice with the water to be sampled at the sampling site. Temperature, pH, electrical conductivity (EC), were measured on site using a calibrated, portable thermometer, pH meter, and EC meter, respectively. The sediments samples, dried, ground and sieved through a 2.0 mm sieve. Sediment pH was determined in a suspension prepared by mixing sediments with deionized water in a 1:2.5 (g:ml) ratio and shaking for 15 min.
Total metal content of the water and sediment samples was determined by ICP-MS. A Computer Program, SPSS, was used for calculating statistical analysis.

There is a positive correlation between cd and Zn ( r = 0.787 ) , lead and arsenic ( r = 0.825 ) and with other metals , this correlation is weakly negative. Positive correlation between Cd and Zn could be a sign of the relationship between these metals and their common input source, considering that these metals are in use in industries and also in the urban environment. Strongly positive correlation between lead and arsenic can be due to common probable sources municipal wastewater .

The relationship between heavy metals in sediment samples is shown in table 2. As it shown, there is a strong positive correlation between nickel and iron (r = 0.952) indicating, correlation between nickel and iron could be an indication of the same source.

Hierarchical cluster analysis was performed using normal data. The results are shown in fig. 1. The elements were placed in four clusters. Cluster1 contains Ni , pH , EC, which have a close relationship with pH and EC . Cluster no. 4 contains Cd, Zn, Pb, as the relationship between them is high and can be stated that the source of the input or control factors is common which is usually associated with industrial applications and discharge of urban wastewater .
The results of hierarchical cluster analysis for heavy metals of sediment sample are shown in fig. 2. Cluster 1 contains As , EC , pH , Ni , Fe , Pb , Zn , Cd , through which Ni and Fe have a strong relationship, possibly geogonically originating. The results are in good agreement with the spearman correlation coefficient.

Conclusion
In this research, the reliability of river for recreational and recreational uses is of great importance. The order of most polluted metals are Ni , Cd , Zn , Cr and Fe they are affected by anthropogenic as well as geogenic activity. is affected by human activities and the relationship between nickel, iron and origin of the earth. Presence of oil sources originating from Asmari formation and untreated wastewater of urban and industrial effluents of masjed soleiman city is the main cause of Tembi river pollution. Although heavy metals enter the human body from different ways, it seems that masjed soleiman city is entering the river and that the Tembi river is a place for swimming and even public fishing , so in long term entry of these metals into the body can cause some complications such as poisoning and dermal diseases.

In this research, the reliability of river for recreational and recreational uses is of great importance. The order of most polluted metals are Ni , Cd , Zn , Cr and Fe they are affected by anthropogenic as well as geogenic activity. is affected by human activities and the relationship between nickel, iron and origin of the earth. Presence of oil sources originating from Asmari formation and untreated wastewater of urban and industrial effluents of masjed soleiman city is the main cause of Tembi river pollution. Although heavy metals enter the human body from different ways, it seems that masjed soleiman city is entering the river and that the Tembi river is a place for swimming and even public fishing , so in long term entry of these metals into the body can cause some complications such as poisoning and dermal diseases.