فهرست مطالب rasool zamaniahmadmahmoodi

One of the sources of pollution in rivers is effluent discharge from fish farms, which decreases water quality for downstream usage. This study investigated the effects of trout farms’ effluent on the levels of physicochemical parameters in Sardab spring.

To assess contamination from the effluent, five trout farms along the margin of the river were selected. In summer and autumn 2016, this study analyzed the levels of physicochemical parameters of trout farm effluent, such as pH, temperature, dissolved oxygen, electrical conductivity, nitrate, ammonia, phosphate and turbidity.

According to the obtained results, no significant differences were detected between pH, temperature, dissolved oxygen, ammonia, phosphate, and turbidity in the two seasons (t-test, p>0.05), but a significant difference between levels of nitrate was found in these time periods (t-test, p<0.05).

The overall level of physicochemical parameters in that summer was higher compared to autumn. The increase in the levels of the investigated parameters in warm weather is probably due to increased temperature and decreased discharge. Rapid population growth in the area of Ardal and the demand for protein foods makes monitoring of the levels of physicochemical parameters of fish farms necessary. In addition to the mentioned factors, increasing the metabolic activities and density of fish in this season can increase the amount of physical and chemical parameters.

Aquaculture includes the propagation and husbandry of aquatic plants, animals, and other organisms for various purposes, including commercial, recreational, and scientific use, which has gained significant attention in recent times. However, its uncontrolled development like any other production activity, can have adverse environmental effects, Thus, the removal of water pollutants is crucial. This study aimed to investigate the impact of a mechanized water disinfection device that uses ultraviolet (UV) radiation at different doses to reduce microorganisms in the effluent of rainbow trout farms.  Also, the efficiency of the device in deactivating pathogens was investigated in different flow rates and water turbidity levels.

The study was conducted in a rainbow trout farm with a 30-ton capacity, located in Kiyar County, approximately 30 kilometers from the center of Chaharmahal and Bakhtiari province. The UV device, at various doses (60, 120, 180, and 240 mW/cm2 = joule), was applied to the farm's effluent, considering different levels of turbidity and flow rates (ranging from 2.5 to 25 liters per second). Water samples were collected both before and after the installation of the UV disinfection device. Subsequently, the average counts of total coliforms, fecal coliforms, fungi, and yeast were calculated with three replications. Probit regression was utilized within the SPSS software environment, with a statistical significance level of 0.001, to examine changes in the removal percentage of microorganisms at different UV doses. Graphs were created using Microsoft Excel 2016 software.

The findings indicated that increased water flow rates and water turbidity reduced the efficiency of removing the targeted microorganisms. The findings indicated that increased water flow rates and water turbidity reduced the efficiency of removing the targeted microorganisms. Moreover, higher UV doses led to a higher removal percentage of total coliforms, fecal coliforms, fungi, and yeast. For instance, at a dose of 56 mJ/cm2, the total counts of total coliforms, fecal coliforms, fungi, and yeast decreased by 1.7, 3.2, 0.7, and 0.86 logs, respectively. However, complete removal of yeasts required significantly higher UV doses, depending on water flow rates and turbidity (up to a maximum of 240 mJ/cm2). Additionally, the results of the probit regression indicated that at doses of 40.50 mJ/cm2, 20.22 mJ/cm2, 30.31 mJ/cm2, and 14.36 mJ/cm2, approximately fifty percent of the yeast population (P<0.001), fungi (Z=13.5, P<0.001), fecal coliform (Z=22.77, P<0.001), and total coliform (Z=6.8, P<0.001) would be removed.

In summary, this research demonstrated that at a dose of 20 mJ/cm2, the gradual elimination of microorganisms begins, but at doses higher than 120 mJ/cm2, the intensity of elimination decreases. Therefore, adjusting the doses of ultraviolet radiation based on the water quality of fish farms can help maintain system health and subsequently increase productivity. The insights obtained from this study can be valuable for commercial water treatment systems and recirculating aquaculture systems. More studies are needed for the efficiency of removing viruses in water by UV rays. It is recommended to construct a sediment pond and employ various water filtration methods, including sand filters, before utilizing ultraviolet rays. This approach aims to decrease the presence of suspended particles in the water and enhance the efficiency of the disinfection system.

One of the major problems of aquatic ecosystems is eutriphication or enrichment of water with nutrients. In this study, the phytoplankton communities in the Karun 4 reservoir were investigated in spring and summer in 2018.

Chlorophyll A and 19 water physicochemical parameters were measured and analyzed at the reservoir in 26 stations. Statistical analysis of data was done in SPSS software. In order to investigate the biological indicators, Simpson and Shannon-Wiener indices were used, and Trophic State Index (TSI) was used to determine the eutriphication status of the lake.

Among the 35 identified genera, the phytoplankton populations mostly belonged to the Nephrocitium, Oonephris, Peridinium, Pyrophacus, Dinobryon, Cyclotella, Diatoma, and Chlorella genera. Also, the population of phytoplankton was more in summer than in spring. The Simpson and Shannon-Wiener biodiversity indices were calculated as 0.835±0.031 and 2.01±0.174 in spring and 0.819±0.041 and 2.02±0.21 in summer, respectively. According to the TSI index, the trophic status of the studied reservoir was in the eutrophic range (50-75). The analysis of the main components of principal component analysis showed that in spring, six components explained 80.847% of the total variance, while in summer, eight components explained 83.287% of the total variance.

The results showed that the Karun 4 reservoir, which is an important water source in Iran, is in a eutrophic state. This may be due to the increase in temperature in spring and summer, the growth of phytoplankton populations, and the increase in the amount of released ions of industrial and agricultural wastewater, which leads to the eutrophic condition in the reservoir.

The examination of the quality of surface water, which is crucial for water supply, has attracted the interest of numerous researchers for a long time. Various indicators are employed to evaluate the quality of water in rivers, and among these indices is the Iran Surface Water Quality Index (IRWQISC).

In this study, water quality changes of Zayandehroud River located in Chaharmahal va Bakhtiari and Isfahan provinces were evaluated using IRWQISC yearly. Physicochemical parameters including BOD5, COD, DO, pH, EC, nitrate, phosphate, ammonium, temperature and total hardness were used to calculate the IRWQISC index in 7 selected stations for 12 years (2004-2015).

 Comparison electrical (EC) values in the stations showed that, EC increased from the upstream to the downstream of Zayandehroud River, and the concentration of parameters in the first station (Kouhrang tunnel) was much lower than the other stations in most years. The results of IRWQISC index showed that values was relatively good in all stations. The best and lowest water quality according to this index were good and moderate in 2006 and 2010 with the values of 73.2 and 49.6, respectively.

Overall, based on the twelve-year average of IRWQISC index, in the selected stations water quality was moderately good in Gharaghush, Cham-nar, Zamankhan Bridge, Kouhrang tunnel, Sudegan and Horeh stations, and was medium in Azadegan station. Identification of pollution sources and controlling inputted pollutants is necessary to protect and prevent the water quality decreasing of the Zayandehroud River.

Soil serves as the primary repository for microplastics, yet their impact on soil-dwelling organisms remains insufficiently understood. This study aims to investigate the influence of varying concentrations of microplastics in soil on the absorption of Cd and Cu by Eisenia fetida within an artificial soil matrix.

The artificial soil consisted of kaolinite clay (20% dry weight), quartz sand (70% dry weight), and Sphagnum peat (10% dry weight). Microplastics, derived from worn-out tire rubber, were incorporated into the soil to establish four concentration levels: 5, 25, 50, and 100 grams of tire microplastics per 500 grams of dry soil. Each treatment was inoculated with ten mature earthworms, weighing between 3.0 and 5.0 grams. After 14 days, samples were collected for ICP analysis.

: The highest accumulation of both metals was observed in treatments with 25, 50, and 100 grams of tire microplastics. The results demonstrated significant disparities in copper and cadmium accumulation in the tissue samples following the introduction of tire wear particles, indicating an augmenting effect of tire particles on metal uptake by the samples. Statistically notable reductions (p < 0.05) in Cd and Cu concentrations were noted in both the control soil and soil containing microplastics, particularly in the 100-gram microplastic treatment for Cd and the 50-gram microplastic treatment for Cu.

Exposure to a combination of microplastics, Cd, and Cu has more pronounced adverse effects on E. fetida, and microplastics enhance the bioavailability of heavy metal ions within the soil environment.

The purpose of this research was to investigate the impact of pH, EC, and organic carbon (OC) on the amount of total nitrogen in the soil of the Zarin Shahr Region using statistical analyses (borderline analysis and step-by-step regression). In the Zarinshahr region, a comprehensive study was conducted for a duration of one year across all four seasons. The study employed GPS technology to select a total of 60 points in agricultural, tree plantations, and bare soil areas while ensuring an average distance of 546 meters between each point. The plots areas were 50x50x20 cm in length, width, and height. The various soil samples collected from these plots were analyzed. Then, the maximum reaction of a biogeochemical process to a certain environmental factor was determined using borderline analysis. According to the findings, the soil's EC exhibited higher readings during the hotter seasons of the year, in comparison to other seasons. Specifically, during the summer, the maximum value of this parameter was approximately 1587 dS/m, while in the winter, the values were nearly 1140 dS/m. Also, pH levels of the soil was generally alkaline. The seasonal variations in soil OC and organic matter percentage were evident, with notably lower values (ranging from 0.04-2.52) in the autumn and winter, followed by a marked increase during the summer and spring (0.12-2.39). Boundary line analysis was used to investigate the relationships between variables and the values of indicators that caused the maximum increase in soil nitrogen. It was ascertained that OC percentage and soil nitrogen percentage exhibited a significant linear correlation in all land uses. Hence, increase in OC percentage resulted in an increase in the total nitrogen content in the soil. The step-by-step regression analysis in a systematic manner revealed that, within the variables under investigation, the percentage of total nitrogen in the soil can be determined based on the impact of two key parameters, namely, EC and the percentage of OC. The results suggest that use of boundary line analysis and step-by-step regression represent a viable approach for determining the effects of the significant factors on the levels of nitrogen content in the soil.

 Investigating the diet of fishes is important in order to investigate the ecological role and understand their position in the food web chains.

In this study, Feeding ecology of Aphanius vladykovi in Choghakhor wetland of Chaharmahal-O-Bakhtiary Province was evaluated seasonally. In this reason, the relative index of gastrointestinal (RLG), condition factor (CF) vacuity index (VI) and food items between male and female, two size classes in the hot and cold seasons were investigated.

Fish diet was primarily composed of crustaceans (Ostracoda, Ampipoda), mollusks (Gastropoda, Bivalvia), aquatic insect larvae (Ephemeroptera, Diptera) and detritus. There was no significant sex and size-related variation in food items. Diet composition was significantly different between hot and cold seasons (p < 0/05). Furthermore, the average of RLG index was 0.885±0.51that indicated the fish was carnivorous.

 In general, in this study, based on the average relative length of the intestine, A. vladykovi is introduced as a carnivorous fish. It is also at an average level in terms of nutrition. The change of season had an effect on the diet of this species, but the studied biological variables such as gender and size were not effective in determining the choice of food items.

One of the most important invasive plant species in Iran is the American mesquite tree (Prosopis juliflora) which has taken the control of a large area of ​​south and southeast Iran. The invasive effect of this species is profound such that it is the dominant species in some areas and the only tree species in most coastal ecosystems of southern Iran. Regardless of draining underground water as the only source of drinking water for local communities and destroying livestock feed, simplifying the ecosystem to only one tree species is a serious alarm of losing the ecosystem balance and causing serious economic and social effects. Considering the importance of the management of American mesquite trees in the south of Iran, this research investigated the spread of American mesquite trees using satellite image processing.

Among the 45 identified species of the genus Proposis, few of them, especially the American mesquite, are known as invasive species. This plant is known as the most threatening invasive plant in Europe. In the red list of the International Union for Environmental Protection, American mesquite is mentioned as one of the world’s 100 invasive species threatening. In this study, an area of ​​1850 km2 between the two cities of Sirik and old Jask was investigated. Pixel-based processing of Landsat 8 satellite images (OLI sensor) was used to extract the tree cover map of the area. The land units (areas covered with similar soil and vegetation characteristics) were produced using the object-oriented processing of Landsat 8 satellite images. Finally, the dominance of American mesquite compared to other trees was calculated in each unit and their canopy density changes were investigated and analyzed using the MODIS vegetation index in a 20-year period. 

According to the results, 13417 ha of the study area is covered by various trees. The American mesquite tree class was the second largest tree class (3991 ha, 29% of the total tree cover) with a heterogeneous distribution and is often located in areas with light and salty soils along the streams. Areas with a strong predominance of mesquite (more than 60%) accounted for 11% of the area which was mostly located in the central parts of the region. 

The results of the image classification showed that the American mesquite heavily occupied areas are mostly located along the main rivers and channels, extending from the eastern highlands towards the waters of the Strait of Hormuz. Thus, proximity to rivers and waterways can be considered as one of the most important environmental factors affecting the spread of these trees. In areas with a strong dominance of American mesquite trees, it was expected that the plant biomass will increase significantly as observed by their high NDVI values. However, the noteworthy point is the increasing rate of the average values ​​of the NDVI index during the last 20 years in the most dominant units, which is now increasing at a high rate with an average NDVI exceeding 0.5 since 2017. This indicates the increasing spread of the American mesquite in the region and even in the areas that have hosted this invasive species for decades.

Management has become an important environmental issue in the last century. This study was conducted to evaluate the knowledge and attitudes of people regarding urban waste management in Shahrekord in 2013. In order to do this study, the city was divided into three districts and randomly, 50 questionnaires (n=150) were distributed randomly. The results showed a significant relationship between the level of education of people and their knowledge about solid waste management (Chi-Square, p<0.05). There was no relationship between the awareness of people and their age and gender (Chi-Square, p<0.05). These results indicated that in a society with a high level of culture, it is easier to manage solid waste. The mean score of awareness of people in this study was 31.88 ± 0.98 (mean ± SD) of 68 score. According to these results, awareness of people in shahrekord was estimated as medium. Therefore, there is a need for planning to change the behavior and attitudes of families and implement programs to increase people's knowledge based on the social and cultural context of the study area. Therefore, in order to improve solid waste management, it should be used to appropriate educational media to promote public culture in relation to solid waste management.

Various indices are used to assess the suitability of water quality for drinking and agricultural uses. The aim of this study is to investigate the water quality of rivers in Beheshtabad watershed for irrigation purposes. Some water quality parameters were measured in 4 selected stations monthly during spring and summer 2013 and 2019 with using the standard methods. Then, SAR, RSC, SSP, KR, PI and MAR indices were calculated. According to the results, the water quality of the stations was in good condition in terms of PI with values less than 80 mg/l, was in good condition in terms of KR with values less than one and in terms of SSP with values less than 200. The water of the studied rivers was hard in terms of total hardness, sweet in terms of total dissolved solids, and had a good condition in terms of permeability index, residual sodium carbonate, soluble sodium percentage, Kelly’s Ratio, magnesium adsorption ratio indices. According to water quality indices, water quality did not change in 2019 compared to 2013. According to the Wilcox diagram, the water of these rivers were in class C2S1, suitable for agricultural use, and according to the Piper diagram were located in Bicarbonate-Magnesium-Calcium group, in the category of water with temporary hardness. In general, evaluation of water quality of these rivers showed that the water of these rivers did not have limitation in terms of agriculture and were almost acceptable and suitable for irrigation.

Today, noise pollution is considered as one of the major pollution of the urban and industrial environment that disrupts the ecological processes of the environment and ecosystem services, physical and mental health of humans and wildlife populations. In this research, the distribution of noise pollution in air and dtermination of noise intensity level in terrestrial habitats for indicator fanua in Khark Wildlife Refuge was done using SPreAD-GIS model. indicator fanua such as deer (Gazella subgutturosa), Whiskered Tern (Chalidonias hybridus), Bridled tern (Onychoprion anaethetus) and Hawksbill sea turtle (Eretmochelys imbricate), Green sea turtle (Chelonia mydas) were studied in this research. The results showed that the noise intensity level from noise sources in the region had no significant negative impact on the presence and distribution of studied species. In other words, the studied species have been adapted to the noise from sources of pollution. In addition, in the vicinity of the sources of noise pollution, there are security and protection conditions for the species to survive in the area without especial problems.

Due to the importance of Pireghar River and discharging of various pollutants in this river, investigation of quality of Pireghar River seems to be necessary. On the other hand, the pollution zoning and give a correct image about quality status of surface water by geographic information system (GIS) to make any management decision with more awareness.

Water samples from 5 station along the river was collected on February 2015, and water quality parameters namely pH, turbidity, temperature, TS, BOD, DO, nitrate, phosphate, and coliforms was examined. Sampling, preparation and analysis of samples was done according to the standard methods. The resulting data was compared with world standards and then analyzed using NSFWQI index and finally path of river was zoned using GIS.

Based on NSFWQI index Pireghar river water quality was fluctuated between good and medium status at all stations. The highest NSFWQI quality index was related to the first station with quality index of 78 and lowest value was related to the fifth station with quality index of 66. As a result, pollution was increased from the first station to the next stations, and water quality has decreased.

In conclusion, for regular management of the river`s water some legislation should be determined and its monitoring program should be continued.

In order to maintain the ecological and biological sustainability of wetlands, it is necessary to have a proper understanding of their physical, biological and chemical environment and to investigate the status of heavy metals in them. The purpose of this study was to investigate the contamination of Choghakhor wetland with arsenic, copper, chromium, lead, zinc and cadmium using MI, HPI, HEI, Cd and IRWQIST indices during autumn 2018. Surface water sampling was performed in 10 stations and the concentration of metals was measured by ICP-MASS. The results of calculation of water pollution indices also showed that the wetland water was within the danger threshold class in terms of drinking according to MI index in all of the stations with a value of 1.04 and within the low pollution class according to HEI index with a value of 0.46. Cd index showed low pollution with a value of -4.96 and HPI showed that wetland water was not polluted with heavy metals with a value of 34.73. Also, according to the results of IRWQIST index, water quality was within the good condition of this index in all studied stations in terms of toxic pollutants with the lowest value of 76.4 in station 1 and the highest value of 80.4 in station 10. Therefore, the water quality of Choghakhor wetland was within the low pollution condition in terms of heavy metals in the water, which requires special attention to the water quality of this wetland in order to prevent further pollution.

Biomonitoring is a simple and inexpensive method for assessment of the quality of the environment. Vehicle emissions introduce high levels of heavy metals into the atmosphere. The use of plant species can be effective in assessing and decreasing air pollution and the levels of heavy metals. This research was conducted to select the best accumulator of lead, zinc and cadmium in the leaves of four tree species, namely Thuja Orientalis, Ulmus umbraculifera, Fraxinus Rotundifolia and Ligustrum Ovalifolium,in four areas in the city of Shahrekord, Iran, with different traffic levels.

For this purpose, testing was conducted in areas with high levels of traffic (Kashani Street, Saadi Street and Shahrekord Terminal) as polluted areas, and Shahrekord University served as control area. In two periods, at the end of spring and the end of summer, leaves were sampled.

Results showed that heavy metal levels in one polluted area, Kashani Street, were higher than in other areas. Also, the highest level of lead and zinc accumulation was observed in the leaves of Ligustrum Ovalifolium with levels of 5.47 and 32.68 mg/kg. The highest level of cadmium, 1.84 mg/kg, was observed in the leaves of Thuja Orientalis.

according to the results,Ligustrum Ovalifolium, Thuja Orientalis, Ulmus Umbraculifera and Fraxinus Rotundifolia were introduced as the best wood species for accumulating heavy metals.

Rivers are one of the main sources of water supply for uses including agriculture, drinking and industry. The purpose of present study is evaluation of heavy metal pollution levels (arsenic, cadmium, chromium, copper, lead and zinc) in the water of Beheshtabad River. Water samples were collected from 7 stations during February 2016, May 2016, August 2017, and November 2017. The concentration of total arsenic, cadmium, chromium, copper, lead and zinc elements was determined by ICP-MASS. Descriptive statistics were performed using SPSS software. Also, spearman test was used for investigation of correlation among metals. The average concentrations of arsenic, cadmium, chromium, copper, lead and zinc in water samples were 0.6±0.48, 0.08±0.02, 2.03±2.27, 2.24±3.23, 1.29±1.25 and 17.08±19.25 mg/kg, respectively. According to the results of the metal index, pollution load, pollution assessment, degree of pollution, no significant or severe pollution was found in the water samples of the Beheshtabad River. According to the results, the level of heavy metals in the water of the Beheshtabad River was natural, and to prevent river pollution, discharging wastes from fish farming and household sewage should be prevented.

Rivers are important as one of the main sources of water supply for uses including agriculture, industry, and human consumption. This study evaluated the water quality of the Beheshtabad River (Shalamzar Spring - Jointing to Koohrang River) located in Chaharmahal and Bakhtiari Province, using the National Sanitation Foundation Water Quality Index (NSFWQI). Using standard methods, this study determined nine water quality parameters: nitrate (NO3), temperature (T), phosphate (PO4), turbidity, dissolved oxygen (DO), biochemical oxygen demand (BOD), electrical conductivity (EC), total solids (TS) and pH, at five selected stations along the river for three months, July to September 2015. Results showed that water quality fluctuated between medium and good quality during the investigation. In addition, according to the mean values of WQI, water quality was classified as medium quality for the three months. Water pollution increased from upstream to downstream in the end of summer because of agricultural fertilizers and wastewater discharge from upstream fish farms and recreation service centers

The present study was conducted to identify pond effluent effects on macroinvertebrate communities of the Parvaz River, located in Chaharmahal & Bakhtiari Province, Iran. Additionally, in order to assess the river's water quality, EPT and HFBI indices were employed. Macroinvertebrates sampling was performed monthly from April 2014 to the end of March 2015. Macroinvertebrates were sampled using the Surber Sampler, with three repetitions at each station. The results of the Hilsenhoff biotic index showed that the level of this index ranged from 4.02 to 4.5. Based on the results of the Hilsenhoff biotic index, the water quality of the Parvaz River was in very good status (possible slight organic pollution) and good status (some organic pollution probable) in April and other months, respectively. The levels of the EPT index showed statistically significant differences in studied stations. Furthermore, downstream stations, especially stations 4 and 5 showed lower EPT values. In conclusion, based on the results of the studied indices, the water quality of the Parvaz River in all investigated stations ranks among rivers with high self-purification, with the exception of the last station.

In order to studing the water quality of Pireghar river, Chaharmahal & Bakhtiari Province, that plays an important role in the main water supply for urban, rural, agriculture and aquaculture, water samples were collected from 5 stations along the river in February 2016 to measure physical and chemical parameters (pH, temperature, turbidity, oxygen biochemical demand, chemical oxygen demand, dissolved oxygen, conductivity, nitrate and phosphate, total suspended solids, total solids) and microbial parameters (total coliform, fecal and heterotrophic bacteria). Sampling methods and analysing was performed according to Standard Methods for the Examination of Water and Wastewater, American Public Health Association. According to the first European standard of the World Health Organization, the degree of bacterial contamination of the river, in comparison with the amount of total coliform was in the third group (ie pollution that be eliminated by costly methods) and in comparison with the amount of fecal coliform was in the first group. The results showed that water quality parameters of river according to the Aquatic standards, Environmental Protection Agency standard, the World Health Organization Institute of Standards and Industrial Research of Iran were in optimum state.

Scientific investigation of drought is essential for water resources management, and reduction it's consequences. But point data of rain is available, where drought affect a range of land. The purpose of this study is spatial analysis of meteorological drought intensity, using geostatistical Kriging in Northern Karun Basin. For this purpose, the standardized precipitation index (SPI) was calculated for 24 rain stations in the area using DIC software.Then, spatial distribution of SPI was determined with ordinary Kriging (OK) submodels: spherical, exponential, linear, Gussian, and linear-to-sill for three years (normal, extremely dry and moderately wet). The results of varigram analysis and error criteria indicated that the geostatistical method Kriging with exponential model due to have lower error rates, has the higher ability in SPI zoning. Finally, the zoning maps if SPI in North Karoun Basin show that in 2007 (extremely dry), drought intensity is higher in eastern parts of basin specially in Broojen station and northern parts of basin like Dashtak, Hiregan and Shahrekord Stations have received more precipitation in 2005 (moderately wet) compared to the rest of the basin. Distribution of drought intensities could be due to rein production fronts and mountainous range direction.

Inorganic contaminants, such as heavy metals enter into terrestrial and aquatic ecosystems from different paths such as erosion and weathering of rock, agricultural and industrial activities, automobile exhaust, sewage and atmospheric subsidence. These heavy metals because of their bioaccumulation potential, toxicity, ubiquitous, and resistance degradation, can be a serious threat to ecological systems and human health. According to Amin et al (2009), more than 90% of heavy metals loading in aquatic ecosystems found in sediments; so, the quality of sediments can be a good indicator of water pollution. In these ecosystems, sediments play an important role as a sink for organic and inorganic contaminants (heavy metals) and provide a history of human-origin emission of pollutants and environmental changes.
To address the sediment contamination by heavy metals, different approaches such as hazard quotients; crop uptake and transformation; concentrations of weakly extractable metal and total heavy metal concentration can be used.
sediment contamination is often assessed by comparing heavy metal concentrations with the relevant environmental references or by quantifying an accumulation factor in comparison to the related background concentrations. Up to now, numerous different indices such as the index of geoaccumulation (Igeo), the enrichment factor, the pollution index (PI) and the integrated pollution index (IPI), the individual element polluted index, the contamination factor and degree of contamination, the contamination factor (CF), the pollution load index (PLI) and the total contamination index (Zs) has introduced to estimate the degree of heavy metal contamination.
Up to now, numerous studies have documented the distribution, origin and extent of heavy metals contamination in sediments of various wetlands. However, wetland sediment contamination has sparsely been investigated in Iran in general and no information is available for the Choghakhor wetland. Choghakhor wetland is one of the most important wetland for waterfowl in Iran which has been exposed to different non-point pollution sources and different contaminants such as heavy metals due to surrounding agricultural and recreational activities and discharge of domestic effluents without treatment. Therefore, the aim of this study was to quantify the concentrations of Ni, Zn, Cu and Fe in surface sediments of Choghakhor wetland. Also assessment of heavy metals contamination using different contamination indices was another purpose of this study.
A total of 52 surface sediment samples were collected randomly from different parts of the Choghakhor wetland; then the samples were placed in clean plastic bags and were transferred to the laboratory for further analysis. 1 gram of sieved sediment sample was digested by using the combination of the three acids: HF, HNO3 and HClO4 whit the ratio of 3:5:7. After cooling the samples, 2 ml of boric acid 7% was added to remove the fluoride residual and with distilled water was reached to volume of 25 cc. The concentration of metals in sediments was measured by flame atomic absorption. For quality control and assurance, standard reference materials and blank samples were used.
Various types of direct (Earth Chemical) and indirect methods (statistical) are commonly used to calculate the contamination of heavy metals in the environment. However, statistical methods are more common than chemical methods because the earth is not alone useful for determining the concentration of background samples, also statistical methods have lower lab work and cost. In this study, a statistical method introduced by Ismailia et al (2014) was used for calculating of the background concentrations. Contamination assessment was carried out using several different indices including Enrichment factor (EF), Geo-accumulation index (Igeo), Contamination factor (CF) and pollution load index (PLI).
Sediment quality assessment guidelines (SQGs) can be very useful in determining the amount of sediment pollution compared with the corresponding guides. In this paper, two sets of guidelines including National Oceanic and Atmospheric Administration USA (NOAA) and the Interim Sediment Quality Guidelines Canada (ISQG) were used. These guidelines express the quality level and degree of contamination of sediments which may have an adverse effect on aquatic organisms. The Correlation and PCA analysis were used to determine the source of heavy metals in sediment samples. Inverse distance weighting method was used for mapping of heavy metals distribution in surface sediments of wetland.
Discussion of The mean total concentrations of Cu, Fe, Mn, Ni and Zn in surface sediments in the whole study area were 15.75, 6076.86, 297.74, 30.07 and 29.87 mg/kg, respectively. Average metal concentrations followed the order Fe> Mn> Ni> Zn> Cu. With the exception of Fe, the concentrations of other heavy metals in the surface sediments of Choghakhor wetland were all lower than the background values.
Mean EF values of heavy metals followed the order: Ni> Zn> Cu> Mn. Average EF values for Ni, Cu, Zn and Mn were 1.34, 2.47, 1.75 and 2.54 respectively suggesting a minor enrichment of these metals. Considering background values, enrichment of heavy metals in this study showed that heavy metals concentrations in sediment samples were mostly controlled by natural and partly anthropogenic sources. Average Igeo values for Ni, Cu, Zn, Mn and Fe were 0.014, 0.032, 0.018, 0.005 and 0.0001 respectively indicating no pollution in wetland sediment samples. However, Igeo is not readily comparable to the other indices of metal contamination due to the nature of the Igeo calculation, which involves a log function, and a background multiplication of 1.5. Mean CF values for Ni, Cu, Zn, Mn and Fe were 0.48, 0.65, 0.59, 0.68 and 0.48 respectively indicating low contamination of heavy metals in wetland sediment samples.
Results of correlation analysis showed that the heavy metals concentrations of sediment samples were significantly correlated with each other at level %1. From this, it could be said that their source was almost the same and which may be derived from the natural sources. Considering PCA analysis, all the heavy metals were well represented by the first principal component, which accounted for over 64.79% of the total variance. The results of PCA agreed well with that of the correlation analysis. As mentioned before, the concentrations of most heavy metals were lower than the background values. Therefore, it could be said that the distribution of heavy metals in sediment samples was mainly controlled by natural sources.
In this study, we analyzed the spatial distributions of heavy metals in the whole area of Choghakhor wetland. The spatial distribution patterns of most of heavy metals, especially Cu, Fe and Ni were generally similar, with increasing concentrations from the north of the wetland to the south nearby villages and residential areas. In other words, the high concentrations or hotspots for the three heavy metals mainly existed in southern parts of the area under study. In addition, the spatial distribution of Mn and Zn concentrations showed decreasing trends from the west of the area to the east.
Therefore, from the above discussion can be concluded that although entire wetland is non-polluted and the heavy metals concentrations in sediment were mostly controlled by geomorphological sources but high concentrations of heavy metals in specific areas or hot spots could be related to human activities especially agricultural activity. In particular, these hot spots are located in environmental guard station, tourist area and residential areas especially villages of Kheder Abad, Saki Abad, Seyf Abad and Khani Abad in the vicinity of wetland.
Results indicated that the average concentrations of heavy metals were all lower than background values. According to the results of Contamination Factor, Geoaccumulation Index and Enrichment Factor, considerable and intense contamination of heavy metals in sediments of study area was not observed. Based on the sediments quality guidelines, the concentration of Ni at whole study area has frequently adverse biological effect on aquatic organisms. Although, the results of the PCA revealed that all heavy metals were mainly originated from natural sources, their spatial distribution maps showed that there were several hotspots located in different parts of the area under study.

Increasing attention is nowadays being paid to contaminants in fish due to their significant effects on the fish and other organisms that live on them. This study was designed to investigate mercury concentrations in the muscle tissues of the two species of Barbus grypus and Barbus luteus indigenous to the Maroon River in Behbahan, southeast of Khuzestan Province. For this purpose, 20 fish from each species were randomly collected from the river over the period from June to December 2009. The fish were then subjected to biometric tests and their gender and age were determined while the Mercury Analyzer AMA254 was used to measure mercury concentrations in their muscle tissues. Examination of the data on age and weight correlations with mercury concentration in the muscle tissues of both species showed that the data did not exhibit a normal distribution but, rather, revealed statistically significant differences. Comparison of the mean values of mercury concentration in the tissues (0.809 mg/kg in Barbus grypus and 0.388 mg/kg in Barbus luteus) with MRL standard limits showed that both species had mercury concentrations below the maximum standard limit set by the EPA. Comparison with WHO standard limits, however, revealed that Barbus grypus had a muscle mercury concentration higer than the WHO allowable limit.