Archives of

Background
Wastewater collected from rural and urban communities which must eventually be returned to the water or soil (1-4). It is well recognized that human activity leads to the accumulation of large amounts of heavy metals in the soil which has been on a global scale (5-8). Numerous chemicals compounds, heavy metals and other industrial wastes in the coastal regions are as the result of discharge of industrial effluents into water in coastal areas. The toxic substances released into the environment and the food chain in different toxic consequences on living organisms (9-11). Cadmium is one of the most dangerous contaminants from soil, which has adverse effects, including preventing the growth of plant roots and shoots, sharp decline in products performance, the impact on nutrient uptake and biological balance. In addition, the metal accumulation in important crops and subsequently enter the food chain, a very serious problem for human health and the animals. Lead is another heavy metal that has unknown biological function and potential toxicity for plants and other living things. Many concerns have been originated for the metal, due to its wide distribution in urban and industrial societies and the potential risk to the environment, human and animal health (12-15). Temby river is one of the rivers in the city of MasjedSoleiman in Khuzestan province's eastern seaboard, Iran. The river crossed the border in the south western city of MasjedSoleyman, receiving municipal sewage and wastewater traditional slaughter of animals in the city and surrounding villages that are discharged into the river without treatment. The river from the edge of the city and the area known as Temby the public promenade and even local public swimming passes. However, due to the salinity of the river water used for drinking, but not due to join the Karon river in the northern city of Shushtar and the impact on the river's water quality is important at the regional level (16,17). Since, there areTamarix shrubs and salty deserts, this plant is often in waterways and rivers, saline and alkaline dry areas grow. The leaves are small and scale-like needles. Using phytoremediation to clean up a solution and inexpensive method directly (no intermediary) - earthy aqueous solutions of heavy metals. Plants with structure and adjustment mechanisms of pollutants to accumulate in high concentrations of pollutants in Rhizosphere are resistance (18). Technical methods of phytoremediation can be used for decontamination of soil, water and air contaminated with low levels of heavy metals and organic materials which were used (19). Manousaki et al (2009) surveyed Tamarix Smyrnensis Bunge for metal bearing properties and the ability to lead and cadmium accumulation. In other words, they used it in order to assess its effectiveness as a cleaning tool for the application of phytoremediation. In that study, they were performed two hydroponic experiments with different concentrations of lead and cadmium. Based on the result, the increased amount of salt in the branches can be increases the concentration of metal (20). Also, Manousaki in another study surveyed Tamarix Smyrnensis Bunge, the Mediterranean region has been widely extended to the accumulation of lead and cadmium heavy metals were examined (21). According to the result of this study, in the plant aerial and roots parts had large quantities of lead and cadmium (21). Rezaei Kahkha and colleagues (2013) studied the absorbtion ability of iron, lead and nickel heavy metals by leaf powder of Tamarix tree. Factors such as pH, contact time and initial concentration of dissolved metal solution with plants were optimized. The results of this study showed that the highest absorption rate at 24 hours and pH=4, as well as the initial concentration of 200 ppm is achieved. Some tests showed the plant uptake by the plant's potential to treatment of heavy metals from 58% for nickel and 65% for iron. Review of the plant's ability to absorb shows that the conventional absorbents such as activated carbon plant in comparison with the power of absorption is good (22). Now, increasing the concentration of heavy metals by microorganisms of the soil is not one of the main challenges in the field of environment. The different effects of these metals are cytotoxic, carcinogenic and mutagenic which are serious risks to human health and other living creatures.
Aims of the study:
The purpose of this study was the evaluation of lead and cadmium heavy metals removal by Tamarix tree in Karon river.
 

Materials & Methods

Methods
Tamarix shrubs and river water samples from Temby were tested after a preliminary review of the three stations in the study area for the existence of lead and cadmium heavy metals in river. Tamarix shrubs were able to absorb them.
Water samples acidified by nitric acid to pH=2 and in combination with other samples were transported to the laboratory. Two liters of water samples put on the stove at a temperature of 80°C until its volume was 50 ml, then, the prepared samples for assessment of heavy metals were measured by ICPMS (23).
Plant samples were first washed with distilled water, then, in order to drying them, they were placed in petri dishes in the autoclave for 48 hours at 105°C (23). After drying, samples were crushed. Then, 2 gr of sample weighed on scales. For digestion of samples, they poured into plastic containers on the water bath (internal temperature 100°C). First, 5 ml of feloridric acid was added to plant samples. Then, 10 ml of nitric acid and 5 ml of hydrochloric acid were added again (20,23). After the completion of digestion, samples were smooth and by 4% nitric acid were reduced to 20 ml. In order to measuring the digested samples, Inductively Coupled Plasma spectrometry was used and poured into a sealed polyethylene container (24).
Statistical Analysis
The coded data were entered in SPSS version 16. Data analysis was performed, using descriptive statistics (frequency, mean and standard deviation for each variable).
 

Results

The results of the experiments showed that the maximum concentration of lead and cadmium before entering sewage were 0.6 and 0.09 ppm during July (Table 1). The amount of lead and cadmium in leaves of Tamarix and river water of Temby listed in table 1.
 
Table 1) The concentration of lead and cadmium in the water before entering wastewater (ppm)

Cadmium	Lead	Months
0.09 0.08 0.06 0.077	0.6 0.5 0.4 0.5	July August September Average

 
Experiments which were conducted in the downstream of Temby resulted in the record of highest concentration of 0.8 ppm for lead in July and the lowest concentration of 0.11 ppm for cadmium in September (Table 2).
 
Table 2) The concentration of lead and cadmium in the water after entering wastewater (ppm)

Cadmium	Lead	Months
0.12 0.13 0.11 0.12	0.8 0.67 0.5 0.66	July August September Average

The results of the digestion and determination of the concentration of leaf samples showed, in the downstream river after the sewage, there were the greatest attraction for lead and cadmium in September 0.065 and 0.1 mg/gr, respectively (Table 3).
 
Table 3) Studied concentration in leaves of Tamarix in downstream after entering wastewater (mg/ gr)

Cadmium	Lead	Months
0.05 0.05 0.1 0.0065	0.04 0.05 0.065 0.015	July August September Average

The following graphs has shown the leaves of Tamarix concentration in the water upstream, downstream and their accumulation.
Figure 1 showed the concentration of lead in different months. Also, based on figure 1, the level of fallen in the water was slightly increased in leaves of Tamarix.
The concentration of cadmium in the water during different months showed in figure 2. An overall level of cadmium in leaves of Tamarix had reduction and slightly increased. Student`s t-Test between the amount of heavy metals in the water of upstream and downstream concentration difference and between the concentration of heavy metals in water and the accumulation in the leaves and stems Tamarix showed significant differences.
Compare the average level of heavy metals in Temby with standard value of heavy metals in drinking water and the water which were used for agriculture and aquatic showed that the average concentrations which were obtained for lead and cadmium within the limits were illegal for drinking water, agriculture and aquatic life (Table 4).
 

 

Figure 1) Lead concentrations in river water Temby and Tamarix tree leaves

Figure 2) Cadmium concentrations in river water Temby and Tamarix tree leaves
 
Table 4) Comparison between the average concentrations obtained in the water upstream and downstream with national standards (ppm)

Heavy metal	Average		Standard for drinking water	Standard for water in agriculture	Water standard for aquatic life
Cd	Upstream   Downstream	0.077   0.12	0.005	0.005	0.005
Pb	Upstream   Downstream	0.5   0.66	0.001	0	0.005