: pollution

The Ziarat River is one of the tributaries of the Qarah-su catchment, and a part of this river flows through Gorgan City. To investigate the environmental hydrogeochemistry of the river, 11 water samples were collected. Physicochemical parameters, the concentrations of major ions and metals, and the biological parameters were analyzed. The obtained results show that pH and EC of the water samples vary from 7.2 to 7.9, and from 701 to 1422 μS/cm, respectively. The highest pH and EC values were observed near the discharging point of cowshed effluents and the Ziarat hot spring, respectively. Based on hydrogeochemical studies, the chemical composition of water samples is mainly controlled by the dissolution process. The water type changed from Ca-SO4 upstream to Na-Cl downstream, probably because of natural and anthropogenic factors. Regarding the major ion concentrations, all water samples are in the acceptable range for drinking usage. Based on the Wilcox diagram, and regarding the calculated residual sodium carbonate and sodium percentage values, the studied water samples are suitable for drinking and agricultural purposes; however, regarding the values of the magnesium hazard index, most of the samples are not appropriate for agricultural usage. Metal pollution indices show that studied samples are highly polluted, especially those samples that were collected at the wastewater discharge points. The values of dissolved oxygen in all samples are within the permissible limits. However, in some stations, BOD and COD levels are higher than permissible values, and the highest amount of these parameters is observed near the discharging point of the cowshed and agricultural effluents. All water samples are microbially polluted, and the lowest microbial pollution is observed in upstream stations. The values of Water Quality Indices indicate that all studied samples are classified as low and very low quality.

This study examines the status of toxic metals in the soil and fish of the Persian Gulf coast, focusing on Bushehr region. The main goal of this research is to identify and evaluate the concentration of heavy metals such as lead, cadmium, mercury and arsenic in soil samples and fish caught from this area. Using the standard methods of sampling and chemical analysis, the method recommended by the Environmental Protection Agency (EPA 3050B) was used as a common acid digestion method, and the necessary data were collected and analyzed. According to the values obtained from five stations on the shores of the Persian Gulf, the concentration of heavy metals, manganese, zinc, chromium and nickel is more than other metals. Also, by examining the average rate of heavy metals in the fish of three Persian Gulf stations, the concentrations of aluminum, zinc, lead, nickel, and copper are the highest. The results showed the presence of high concentrations of some toxic metals in soil and fish, which can be caused by industrial activities, agriculture and oil pollution. These findings raise concerns about ecosystem health and food safety in Bushehr region and emphasize the necessity of management and monitoring measures to reduce pollution and protect natural resources. In general, heavy metals are toxic to the body at very low levels. Aluminum, lead, cadmium, and nickel have a higher degree of toxicity, therefore, the increase of these metals in the tissue of fishes is associated with many risks. The main mechanism of heavy metal toxicity includes the production of free radicals to cause oxidative stress, damage to biological molecules such as enzymes, proteins, lipids, nucleic ‎acids and DNA damage‏.‏

Polyaromatic hydrocarbons (PAH) with a benzene ring are petroleum compounds and are known as the most important cause of environmental pollution. Phenanthrene and anthracene are PAHs found in the aquatic environment. In the present study, the effect of these two substances on a freshwater algae, Spirulina platensis, was investigated at biochemical levels. Algae mass cultivation was performed in laboratory conditions in nine treatments and 27 repetitions of anthracene (5, 25, 50, 250 mg/l) and phenanthrene (10, 50, 100, 500 mg/l) for 72 h. A control treatment with no anthracene and phenanthrene was also considered. The amount of malondialdehyde (MDA) in the treatment of phenanthrene and anthracene increased compared to the control treatment, which was significant at the 5% level, but the amount of MDA in the treatment of phenanthrene at a concentration of 10 mg/L did not show a significant difference (P>0.05). Sugar content showed a significant difference except in the concentration of 10 mg/liter of phenanthrene (P<0.05). Proline content increased significantly in response to both hydrocarbons (P<0.05), There was a significant increase in proline in both anthracene and phenanthrene treatments compared to the control group at a probability level of 5%. Catalase activity showed significant changes between the treatments compared to the control (P<0.05). The amount of total protein significantly increased in phenanthrene stress and significantly decreased in anthracene stress in all concentrations compared to the control group (P<0.05). The results showed that both hydrocarbon substances at different concentrations had significant effects on the biochemical characteristics of spirulina algae.

Although milk and its products are considered as a useful food rich in essential nutrients for the growth, development and maintenance of human health, in some cases, it contains harmful substances that can cause various diseases (many cancers) in different people. If aflatoxins enter the human and animal body, they can put the body in serious dangers. Although the rumen of ruminant animals, including cows, sheep, and goats, is the first and most important defense barrier against the entry of mycotoxins, especially aflatoxins, nevertheless, some studies show their entry into milk. In recent decades, the presence of aflatoxin M1 has been identified as an important mycotoxin in milk. Contamination of milk and its products with aflatoxin M1 is considered an important issue, especially for developing countries in the last decade. On the other hand, the entrance of aflatoxins into livestock products, especially children and babies who use these substances, is very sensitive and of particular importance. Therefore, in this article, an attempt has been made to investigate how aflatoxins enter milk and livestock products, as well as their nutritional characteristics and effects.

The ecology of the Earth is changing drastically due to the excessive use of energy and its inadequate basket. These changes have severely influenced the world, leading to certain changes, such as the melting of polar ice caps, rising water levels, forest fires, and the increase in hurricanes and tornadoes on Earth. These environmental disasters should be rooted in the developments resulting from the industrial revolution, the launch of industrial systems instead of traditional systems, and changes in the method of utilization. In the early 1970s, these developments caused the energy crisis set alarm bells ringing, exposing the world to two major crises, viz. limited fossil fuel resources and increasing environmental pollution. Since then, the main concerns have been economic development and access to alternative sources because all countries are facing energy shortages and resource problems, particularly fossil fuels, in view of global energy. The growing trend of energy consumption, particularly oil, is ongoing around the world. Despite all the extensive research and investment in alternative and renewable energy sources worldwide, oil and gas consumption has been in the first place in recent years, and the economic dependence of countries on oil and gas supply is on the rise. Currently, extensive efforts are ongoing worldwide to replace new energy sources, and good results have so far been achieved for the appropriate use of energy forms. In the present world, energy is generally found in three main forms of fossil fuels, nuclear energy, and renewable energy.

This research is descriptive-analytical in terms of methodology, an applied study in terms of targeting, and a library-documentary study in the method of data collection. During the study process, the following goals are pursued in this article:• Understanding energy consumption in the world Description of energy consumption and its impact on air pollution  The need to use nuclear energy in Iran The energy crisis has persuaded all countries in the world to reduce energy consumption and find new sources to meet their needs (Mousavi et al., 2017). The Paris Agreement is one of the commitments concluded to prevent the increase of greenhouse gas emissions and the resulting temperature rise. According to the agreement, signed by more than 160 countries, the increase in global average temperature should be limited to less than 2 °C compared to the level before industrialization, and global warming should be limited to 1.5 °C (Dong et al., 2018).According to forecasts, energy consumption in Iran will increase to 10 million barrels of oil equivalent (BOE) per day in 2025. The average annual growth of energy consumption in Iran has been about 5.5% in the last 10 years and, if this trend continues by 2025, the energy consumption in the country will reach 3752 million BOE. In that case, the crude oil exports of Iran will reach zero based on the current state of production. Iran was the fifth largest producer of crude oil in OPEC in 2020 and the third largest producer of natural gas in the world in 2019 (Steamers, 2017). Nuclear energy Nuclear energy cannot be considered a source of renewable or perishable energy. Although its reserves are so large that will not deplete in the predictable future, the fact is that its reserves will decline with the gradual use of nuclear energy and deterioration due to radioactivity, eventually being exhausted the same as fossil energy sources. Nuclear energy is important regarding the supply of global energy and low environmental degradation compared to fossil fuels. The majority of accidents at nuclear power plants have resulted from operational malfunctions or insufficient preventive safety tools, hence, both factors are being seriously and effectively addressed in ongoing research. Therefore, it can be predicted that a substantial part of the required global energy in the future will be supplied by nuclear energy (Evins, 2013).With some of the largest proven oil and natural gas reserves in the world, Iran is ranked as the third and second largest possessor of oil and natural gas, respectively, in the world in 2020. At the end of 2020, oil reserves in Iran accounted for 25% and 12% of those in the Middle East and the world, respectively (Vijayalakshmi, 2018).Since the cost of fuel required by a nuclear power plant is 10% of that in a similar fossil power plant, and given a 50-year lifetime of a nuclear power plant, the difference in cost amounts more than billions of dollars based on the current prices. As with other countries in the world, population growth is on the rise in Iran and is dependent on energy to develop the level of social welfare. On the other hand, in an era faced with the development of cities and metropolises, Iran needs to save its oil resources for future generations due to the need for development in parallel with other countries in the world. Instead of consuming and selling existing sources, they should be utilized in important manufacturing sectors and the petrochemical industry. Therefore, it is necessary to achieve an appropriate alternative source with the centralization ability, especially in metropolitan areas, and the possibility of replacement in terms of environmental health and economic development because there is the need for more energy in the current world and, consequently, in our country. On the other hand, the increase in the cost of fossil fuels and their impact has led to global warming and the development of environmental pollution. Therefore, nuclear energy is also an appropriate source of energy supply in our country considering the aspects and effective factors in the use of nuclear energy in first world countries. Additionally, the geographical location of Iran and the potential capabilities of its natural resources make the use of nuclear energy a positive and fruitful step towards environmental sustainability and no use of non-renewable energy because its use can be controlled for environmental protection, with an abundant and degradable primary source. As with other energy sources, nuclear fuels have destructive environmental effects during uranium mining and nuclear waste disposal but are not comparable to fossil fuels, and power generation from nuclear power plants lacks the pollution of existing power plants. Moreover, another feature of this type of energy is the lack of greenhouse gas emissions.

The increasing growth rate of world population, industrialization, and the emergence of various technologies led to the increased energy demand and prediction of limited and important resources of oil and gas as well as their excessive consumption. This has made the process of energy achievement and its conversion methods one of the most important issues in political, economic, and social life dimensions to the extent that it has affected the daily lives of individuals, families, countries, international policies, and national/international development plans. Nowadays, the need for survival and global development depends on energy production and consumption. On the other hand, energy statistics indicate that two important issues coincide with increasing human demand for energy in the world and Iran. The first is the increased demand for energy given the deficiency of existing sources, and the second is the increase in environmental pollution by the use of current energy sources. To fulfill these needs, humans seek a logical solution to respond positively to environmental friendliness through profit-making and utilization in economic dimensions. Man has so far achieved nuclear energy with numerous efforts. In the current developing world, man can satisfactorily take advantage of nuclear energy instead of traditional sources and methods and fossil fuels. Nowadays, humans know that they can properly and sustainably exploit this environmentally friendly energy. Meanwhile, our country can save its oil resources for future generations and, simultaneously, benefit from using those resources in the prosperity and development of mother industries such as petrochemistry. The replacement of fossil fuels with nuclear energy alongside other renewable energy sources can provide the best economic and environmental benefits, particularly in power generation, by using climatic and regional capabilities as well as specialized manpower in line with global development.

Today, water pollution is a global challenge that, in addition to developing countries, is also present in developed countries. This global challenge is linked to economic growth, environmental health, and the health of billions of people. Water can be consumed by living organisms directly or indirectly by entering agricultural products, and the quantity and quality of life of living organisms, especially plants and humans, will suffer from serious problems. Today, agriculture is still recognized as the most important source of water pollution in the world and industrial activities are an important complement to this pollution. Various factors can cause water pollution, the most important of which are microbial, chemical, and heavy metal pollution. Heavy metals generally reduce the growth and yield of plants, and their effects on humans can lead to a variety of diseases, including cancer. Although prevention is the most important way to control water and heavy metal contaminants, there are several ways to remove them from the environment, one of the most important of which is phytoremediation. Phytoremediation is a type of bioremediation in which the plant is used to reduce the concentration or toxic effects of pollutants in the environment. This article reviews the types of heavy metals and their sources, the effects of heavy metals on humans and plants, and methods for repairing soils contaminated with heavy metals.

Sediment samples were collected from 8 sites in the northern areas of Qeshm Island, Iran to determine the total and partial concentrations of heavy metals including copper (Cu), lead (Pb), nickel (Ni), cadmium (Cd), and Iron (Fe), in February 2016. A combination of nitric acid and perchloric acid was used to determine the total concentrations and sequential extraction method was used to analyze the partial concentrations of different geochemical parts of the sediment. Metal concentrations were measured by flame atomic absorption spectrometry. Contamination factor (CF), pollution load indices (PLI), enrichment factor (EF), geoaccumulation index (Igeo), risk assessment code (RAC) and potential ecological risk (PER) were calculated to determine the ecological risk. The results showed that the concentrations of heavy metals were Fe>Ni>Pb>Cu>Cd, respectively. The results of sequential extraction showed that Cd (25.98%) and Cu (21.40%) had the highest bioavailability among the other heavy metals. Most of each element was in the part of reducible (Fe-Mn oxide bound) (F3) and residual (F5). According to the RAC, only Cu and Cd were identified as high-risk at Station 5, and for other stations and other metals, the results showed low, medium or no risk. Evaluation of enrichment factor showed significant contamination for most of the metals tested, including Cd, Ni and Pb, which confirms the results from other indices. Finally, it can be said that the results of various indices that have been measured in relation to the mentioned heavy metals, showed that these elements have low to moderate pollution in the study area.

Heavy metals contamination of soils is one of the main environmental problems. Heavy metals are considered one of the most dangerous groups of pollutants because of their toxicity and stability. The biological and ecological importance of heavy metals is due to their characteristics, toxicity, persistence, and bioaccumulation. Heavy metal pollution not only directly affects the physical and chemical properties of the soil, but also reduces biological activity and access to nutrients in the soil and poses a serious threat to human health. The concentration of heavy metals in the soil varies depending on the type of parent rock, mineralization and soil formation conditions in different areas. soils from ultramafic rocks and mainly serpentinites from these rocks have a higher concentration of chromium, nickel and cobalt metals than non- serpentinite soils. Therefore, ophiolites can be named as one of the most important natural pollutants. The Virani area is located in Khorasan Razavi province, 15 km northwest of Mashhad. The purpose of this study is to investigate the status of heavy metal contamination in serpentinite soils resulting from the ophiolite complex of Mashhad.

In the present study, 20 soil samples (10-30 cm depth) were collected and the concentration of arsenic, cadmium, nickel, cobalt, coppe, chromium, zinc, manganese, molybdenum, lead, antimony, titanium, silver, aluminium and iron were measured using atomic absorption spectrophotometry. To prepare the samples, first 1 g of the sample powder was dissolved in nitric acid along with fluoric acid. The solution was heated in a Teflon dish at 60 ° C until completely evaporated and the sample dried. The sample was then dissolved in 100 ml of 4% HNo3 solution. Also, some other soil properties including PH, organic carbon, cation exchange capacity and soil texture proportions were measured. The pH of soil samples was measured using water and KCL 1 with a ratio of 1 to 5.2 soil solution. PH soil of the samples was measured by PHmeter modle UB-5, organic carbon was performed by the Walkley-Black method, which adjacent the soil with concentrated sulfuric acid and bichromate, and after the reaction, the remaining bichromate was calibrated with ferroammonium sulfate, and soil texture by hydrometric method. Based on geochemical data, index of enrichment factor (EF), geoaccumulation (Igeo), contamination factor (CF) and statistical analysis (cluster and principal component analysis) calculated for evaluating contamination in this area. The pearson correlation has used to find the association between the studied elements The statistical analysis and modeling were performed in SPSS, GIS and Excel software’s environment.

The results of measuring the physicochemical properties of the soil of the region showed that the value of PH all samples are neutral to relatively alkaline and varies from 7.71 to 7. 85. The studies samples show that the value of EC from 12.32 to 13.88 and organic carbon 0.842 to 0.971 percent. The soil samples were classified loam. Considering the relatively uniform PH in all samples and the similarity of organic carbon and cation exchange capacity in all samples, it can be concluded that the soil of the region is formed under similar physicochemical conditions and these factors have no effect on the distribution of heavy metals. The results of heavy metal analysis showed that aluminum has the highest concentration and cadmium has the lowest concentration in the soils of the region. The trend of changes in the concentration of heavy metals in the soil of the region can be more related to the rock units of the region. Serpentinite soils containing nickel, chromium and cobalt can be found in the structure of silicate minerals such as serpentine, talc and chlorite, as well as oxide minerals such as chromite, magnetite and various hydroxides. These minerals work better with heavy metals in the release of heavy metals. The calculated enrichment factor (EF) values vary 1.042 to 11.83. The results demonstrate than in the soil of the study area some heavy metals such silver, arsenic and antimony higher enrichment, chromium, nickel, lead moderate enrichment and zinc, copper, cadmium, iron, molybdnyum, cobalt, titanium, aluminium, manganes are enriched to a minor degree. The results geoaccumulation index (Igeo) than in the soil of the study area some heavy metals such silver moderate polluted, chromium, nickel, cobalt moderately polluted to un-polluted and cadmium, iron, zinc, copper, lead, titanium, antimony, molybdnyum, aluminium, manganes, arsenic are un-polluted. The spread of ultramafic and serpentinite rocks in the western and northwestern parts of the region has caused more pollution in these areas. The calculated contamination factor (CF) change from 0.39 to 4.617, indicates that the soil samples changes from low contamination to strong contamination. The samples are extremely polluted with silver. The contamination values of chromium, nickel, arsenic, lead, manganes are moderately contamination and zinc, copper, iron, aluminium, cadmium, titanium, antimony, cobalt are low contamination. The Pearson correlation has used to find the association between the studied elements. There is a high positive correlation between the chromium, nickel and cobalt elements. Investigation of the cluster analysis (CA) relationships between potentially toxic elements in the soils showed that the studied elements could divided in to two main cluster. The first and second branch can be divided into two sub-branches based on the branch weight and similarities. The cluster graph shows that chromium, nickel and cobalt were highly correlated with each other, indicating the same origin of the metals in the soils. To ensure, principal component analysis (CPA) was applied to find metal sources in the soils. These results show the geochemical behaviors and sources of chromium, nickel and cobalt are different from other elements. The elements can be originated from the mafic and ultramafic rocks in the western and northwestern if the area and the presence of these elements in the soil can attributed to their lithological origin. The entry of nickel into the circulatory system through agricultural products, respiration or consumption of groundwater with high levels of nickel can cause damage to internal organs, disorders of the body's defense system, various cancers of the blood and bone marrow, local infections, inflammation and chromium, Followed by neurological, digestive problems, liver damage, kidney damage, heart palpitations, skin damage and lung cancer. Biological methods such as phytoremediation, prevention of leafy crops such as cabbage and lettuce, prevention of livestock grazing and planting of resistant and serpentine tree is the region reduce, the negative effects of heavy metals in the soil.

Water can be considered as one of the most important factors of growth and economic development of each country. The lack of water resources and low efficiency of methods of operation in the country has made the country to use excessive groundwater resources and have environmental problems in Iran. In this study, environmental efficiency of water resources across the country in order to evaluate the efficiency of the variable - based model (slack - based) model on relaxation was considered. Then, in this study, using the dynamic panel model with the application of the generalized moments of space in 2011 - 2018 in 31 provinces, the effect of threshold extraction of water resources was studied. The results of the overall efficiency of the first stage were significantly higher than the performance of water resources in the second stage and the overall efficiency was close to the effectiveness of the second stage and the efficiency of the second stage determined the overall effectiveness of the environmental efficiency of Isfahan, Kerman, Semnan, North Khorasan, South Khorasan, Razavi Khorasan, and Yazd. The SAR space variable had a coefficient 0.142, which indicated that the efficiency of water resources across the provinces, where the geography location was independent of political divisions, had spatial effects on the real GDP of the neighboring provinces. overall efficiency of water resources had sudden spatial effects and the overall efficiency of regions was affected by neighborhood regions. Direct and indirect effects of internal water consumption, opening degree and industrial structure had meaningful effect on the overall efficiency of water resources in Iran. The spatial effects of internal water consumption and industrial structure had a significant effect. In order to improve the efficiency of water resources, the government, citizens and farmers should focus on solutions such as reducing pollution, saving domestic water and converting industrial structures. It was suggested that in the lower - efficiency oblasts with less efficiency in order to improve efficiency, production structures and technologies with the use of more efficient water resources rather than destructive and polluting technologies, the government controled and improved the efficiency of the country 's water consumption by implementing strict laws to protect the country 's water resources.

Caspian forest of Iran with an area of approximately 1.8 million hectares with more than 80 species of trees and 50 species of shrubs have been identified as the oldest forests in the world which belong to the third geological period. Increasing growth of human population and the development of industries to response of its demands, cause to production of various types of waste. Select landfill without regard to environmental issues poses many threats to the environment, choosing the right place and location for landfill is essential. Accumulation of waste in the forest increases heavy metals such as lead, cadmium, nickel and chromium. Some trees are very sensitive to leachate from sewage and dry out quickly. Hyrcanian forests are one of important reserve habitat in our country. There are many various natural and human threats on it that cause many problems in its ecosystem. One of these threats is landfill forest. Also, the lack of effective studies to determine the negative effects of landfills on forest ecosystems, the purpose of the present study identifies the negative effects of landfills in forest areas in Zarandin region of Neka city.

The purpose of this study is to investigate the effect of landfills in forest lands on heavy metals (lead, cadmium, nickel and chromium) and tree species in Zarandin region. The study area is a forest ecosystem around Zarandin landfill with an area of about 26 hectares located 9 km southeast of Neka city. The important tree species and shrubs of the area can considered to Zelkova carpinifolia (Pall.) k.koch, Parrotia persica C.A.Mey , Quercus castaneifolia C.A.Mey, Carpinus betulus L., Acer velutinum Boiss, Alnus subcordata C.A.Mey ,(Acer cappadocicum Gled ,Diospyros lotus L., Mespilus germanica L, Crataegus microphylla k.koch , Prunus divaricate Ledeb. Along the leachate channel, 10 sampling stations were selected up to a distance of 1000 meters from the landfill. Stations were chosen at intervals of 100 meters along the channel. each sampling station includes of two points; one point at the edge of the channel and the second point at a distance of 20 meters from the channel. Soil samples were taken with three replications. A forest area adjacent to the landfill with similar environmental and floristic characteristics but far from the direct impact of the landfill was selected as a control area. in the control section 10 samples were taken. At each station, soil samples were prepared for laboratory operations. Vegetation inventory were also performed in all plots. The selected plots were similar in terms of slope, general direction and height to minimize the impact of environmental conditions and topography on the comparisons. Plots 20 × 20 m were used to study tree and shrub species and plots 1 *1 m were used to analysis of tree species generation and grass coverage.Determination of heavy metal concentrationsSoil samples were tested to determine the concentrations of the heavy metals lead, nickel, cadmium and chromium. For chemical analysis, the concentration of heavy metals in the soil is weighed 1 gram of each sample dried by a digital scale and poured into Erlenmeyer containers. Then 10 cc of concentrated nitric acid is added to it and placed on a digester (Hot block digester) and placed at a low temperature of 130 ° C for 1 hour and then 400 cc of hydrogen peroxide is added to it. Samples are filtered with S&S filter paper in 50cc c-balloons and the filtered solution is reduced to 50cc using deionized water and poured into plastic containers (Heinrichs et al., 1986).Enrichment factorIn order to investigate and evaluate soil contamination in the study area, the results of heavy metal analysis with NFSI index (Utermann et al., 2019) were compared and the enrichment factor of all samples was calculated.The concentration of elements compared to the normal concentration was measured using the enrichment factor. The following equation was used to calculate this factor.EF = Se / ReEF is the enrichment factor, Se is the concentration of elements in the soil and Re is the concentration of elements in the reference material. The classification of enrichment factor values in determining the degree of contamination is given in the table below (enrichment factor value classification table) (Bhuiyana et al., 2010).Table 1: Classification of enrichment factor valuesFactor amount Pollution degreeNo pollution 0No pollution to moderate pollution 1moderate pollution 2Medium to strong pollution 3strong pollution 4strong pollution to Very strong pollution 5Very strong pollution 6The results showed that the pH and EC in the soil of the contaminated area increased and the concentration of all studied metals in the contaminated area compared to the control area showed a significant difference (P <0.05). The density of Parrotia persica, Carpinus betulus and Zelkova carpinifolia in the infected plot was lower than the control plot. Quecus castanifolia did not show a significant difference but the number of Acer sp in the infected area showed a significant increase. Also, reproduction of Carpinus betulus, Quecus castanifolia and Zelkova carpinifolia in the infected area, a significant decrease and Parrotia persica and Acer regeneration in the infected plot showed a significant increase.

Finally, the results of this study showed that the acidity, concentration of lead, nickel, chromium, cadmium in the soil of the landfill and its margin was significantly higher than the soil of the control area. Soil factors such as pH and EC was high in soil samples in infected area. Also, the results of density of tree and shrub showed that the difference in species density between infected and control plots was significant in all species except Quecus castanifolia. The number of Parrotia persica and Carpinus betulus and Zelkova carpinifolia tree stocks showed a significant decrease in the infected area.Finally, the results of this study showed that municipal waste landfilling has significant effects on the chemical properties of forest soil, so providing the necessary facilities for waste management such as waste incinerators and compost factories in these areas is necessary. It is also necessary to conduct more extensive studies in order to obtain comprehensive information for optimal forest management and reduction of pollution and its spread in forest areas.

This investigation was designed to study the effect of heavy metal pollution of soil around the BidBoland 1 gas refinery site on morphological and biochemical characteristics of mung bean. A pot experiment was conducted in a completely randomized design with four replications. The soil sampling was carried out at three stations in about 500, 1000 and 1500 m away from Bidboland gas refinery site. The control soil from a farm away from refinery site. Soil analysis indicated that the soil around the refinery site was contaminated with cadmium, chromium, lead, vanadium, mercury and arsenic, which their contents reduced by increasing the distance from the refinery site. The mung bean seeds were cultured in control soil and three levels of contaminated soil with heavy elements. The results showed significant changes in plant growth and photosynthetic traits of mung bean plants in response to heavy metal pollution of soil. Soil contamination with heavy metals significantly reduced the amount of chlorophylls a and b, total chlorophyll, carotenoids, photosynthesis, chemical quantum function of photosystems (PIABS), intercellular CO2, transpiration, and water use efficiency. The highest and lowest reduction in photosynthetic parameters was observed in the soil collected from distances of 500 and 1500 meters to the refinery, respectively, as compared to the control soil. Heavy metal pollution increased the proline content. Based on the results of present study and the danger of heavy metals pollution on mung bean growth and photosynthesis, it is suggested to avoid cultivation of crops around the gas refinery site.

For this purpose, the station in the region of Laft, which gasoline smuggling in the intertidal area ,and at the same time, selected three similar stations in the Tabl area as a blank station, and were sampled seasonally from Autumn 2015  to Summer 2016. The total abundance of macrobenthos in Laft station (457/ m2) and Tabl stations (727 /m2) was concluded, and the maximum and minimum relative frequencies of macrobenthos in Laft estuary are Spiroloculina sp. (11.4%) and Tellina vernalis (3.8%), respectively, and in the tabl(blank station), this ratio is related to Cossura longocirrata (21%). and Spiroloculina sp. (9.8%).The results of the t-test showed that there were significant differences between the Laft and the Tabl stations(95% ), based on the tree chart derived from the cluster test , the studied regions in two regions can be divided into the first and second groups in terms of time.In addition, due to the correlation coefficients (Canonical Correlation) for each group, in particular at the Tabl station, the functions formed have a high separability to the resulting functions belonging to the Laft station, which can indicate the stability and more sustainability in the Tabl station macrobenthose communities than the Laft station, or, in other words, the ecological potential of the bottom of sea at Laft station is influenced by the gasoline smuggling less efficient than the Tabl station. The results of biodiversity indices changes showed in the two stations, showed that there are differences between the Marguerite, Shannon-Wiener and Simpson indices and Hill number between macrobenthose communities of the two stations(P<0.05). The maximum and minimum richness  Margalf indices were concluded in Tabl station ((3.28 (±0.12)) and Laft estuary station (1.9 (0.13)), respectively.

In recent years, earthworms have been used to clean soil contaminated with heavy metals. The aim of this study was to investigate the Bioaccumulation factor of earthworms in soils contaminated with heavy metals. The sewage sludge added to soil at levels of 0, 10, 20, 30, 40 and 50 tons per hectare. Earthworm (Eisenia foetida) was added to the polluted soil in order to study the effect of organic amendments. The total concentration and fractionation of heavy metals, the weight and mortality of earthworm were evaluated after 42 days. Sampling of earthworms was performed at eight weeks. The maximum accumulation of heavy metals by earthworms was found in 20 tons per hectare treatment. Bioaccumulation factor was more than 1 for the zinc and cadmium which shows the ability of earthworm (Eisenia foetida) for accumulation of these metals in the contaminated soil with heavy metals. The loss of weight was found for all treatment during the experimental period. Despite earthworm weight loss in all treatments, the highest number of deaths was observed in the control group which were free of sewage sludge. In general, the results showed that the use of earthworms could play an important role in clearing heavy metals in the soil.

This study was conducted to evaluate the physico-chemical parameters and heavy metals (Lead and Cadmium) levels in the water of the Damavand River. Samples were collected from 10 stations over a three month summer period in 2015. parameters were measured according to the standard methods for the examination of water and wastewater and the institute of standards & industrial research of Iran guidelines. Temperature, pH and turbidity were measured in situ. There were no significant differences between temperature, pH, turbidity, electrical conductivity, BOD, calcium, magnesium, sulphate, nitrate and phosphate in the stations at 95% confidence level. Significantly (P<0.05) highest level of COD was for station 10 (24.47±7.45 mg/lit) and the lowest one was in station 4 (8.34±5.56 mg/lit). Significantly lowest levels of lead and cadmium were obtained at station 1. There were no significant variations (P>0.05) between lead levels in the stations 8, 9 and 10 and also between cadmium concentrations in the stations 8 and 10; these stations had the highest levels of the heavy metals. result was due to effluents from industrial units in the downstream of the river. were significant differences between temperature, pH, BOD, calcium, magnesium, sulphate and phosphate in the months at 95% confidence level

CO pollutant gas is an odorless and highly toxic gas and is one of the toxic pollutants caused by incomplete combustion in cars. In this study, the amount of carbon monoxide and hydrocarbon pollutants produced by gasoline and CNG vehicles has been analyzed. These studies have been done according to the amount of vehicle mileage. Attempts have been made to select vehicles so that the amounts of CO and HC emissions produced in gasoline and CNG vehicles are in the same range for a more accurate comparison. According to studies, the amount of carbon monoxide pollutants produced in a CNG vehicle with 733,000 km is almost equal to a gasoline vehicle with 242,000 km. Also, the minimum value for a CNG vehicle with 210,000 km is 0.39. While in the same mileage for gasoline vehicles, this value is estimated at about 0.58. In the case of hydrocarbon pollutants, the conditions are better for CNG vehicles and they produce fewer pollutants in the same kilometers. Thus, the amount of hydrocarbon pollutants produced in 733,000 km of CNG vehicles is slightly different from its amount in 242,000 km of gasoline vehicles.

Today, vehicles are considered as one of the main causes of pollution in the world. Therefore, the issue of increasing environmental pollution has caused serious strictures to be considered to control the amount of pollution produced by vehicles. CO pollutant is a colorless, odorless and highly toxic gas that is one of the causes of incomplete combustion in cars. The toxicity of carbon monoxide is due to the fact that the tendency of hemoglobin to combine with CO is 200 to 250 times that of oxygen. Therefore, due to the importance of environmental pollutants created by cars, many researchers have done research in this field. Mehdi Niajalili et al. have investigated the effect of using optimal wires in the car ignition system on its emissions. The researchers used low-resistance wires in the ignition system and investigated the effect of using these wires on pollutants such as CO, HC, CO2 and O2. The researchers finally stated that the use of optimal wires can reduce the CO parameter in the output of healthy vehicles by up to 60%. It also reduces the amount of HC pollutants to an acceptable level.Dehghan et al. have also researched on the emissions of several vehicles. These researchers conducted their research in the city of Shiraz. They analyzed CO, CO2 and HC pollutants in vehicles and evaluated the relationship between the year of production of the vehicle and the amount of emissions of these pollutants. They stated that there was a significant and negative relationship between the year of production and the amount of CO and HC production, so that with the increase of the year of car production, the amount of these pollutants decreases.In this study, 8 Pride cars with different vehicle mileage and production years have been analyzed and the CO and HC parameters produced by these cars in two categories of CNG and gasoline based on the vehicle mileage of the said car have been investigated.

In this section, eight cars, including four gasoline cars and four CNG cars are considered. Then, using the vehicle gas analyzer device called QROTECH (QRO-401) the exhaust gases of study vehicles are recorded and analyzed. This device, which has high accuracy and strength, can be used within two to eight minutes after turning on. This emission control device is also capable of measuring CO, HC, NOx, O2 and CO2 emissions. It is noteworthy that all study cars are Pride type and have similar conditions and are considered only with differences in the fuel system (gasoline and CNG). In the selection of cars, the criterion of the range of pollutants produced and the mileage of the car is considered and the year of production of the car has no effect on its selection. In addition, there is no obligation to include the production range of vehicle pollutants in the standard range.In the next step, the reported values are analyzed. As mentioned, the criterion for selecting cars was the mileage of the car and the year of production did not affect the selection of studied cars. In addition, vehicles have been selected so that the high and low percentages of CO gas for both groups of vehicles are in close range, so that the results can be better analyzed. According to research, the percentage of CO pollutants in CNG vehicles is much lower. So that the CO pollution produced in 733000 km in CNG vehicles with the same parameter in one third of a kilometer of gasoline vehicle mileage is equal. According to investigation, with the increase of vehicle mileage, the amounts of CO and HC emissions increase, but according to vehicle data, the growth of CO emissions in gasoline vehicles is higher. According to research, similar results are obtained for HC. That is, with the increase of mileage of gasoline vehicles, the growth rate of HC pollutants increases more than CNG vehicles. The amount of this pollutant at 733000 km in CNG vehicles is estimated at 230 ppm. However, in gasoline vehicles, the amount of HC pollutants at 242,000 km is measured at 240 ppm.Conclusion Due to the fact that vehicles are one of the most important sources of pollution in cities, this paper examines the impact of vehicle mileage on the production of CO and HC pollutants in gasoline and CNG vehicles. These cars, all of which are Pride, have similar physical conditions and are selected only with differences in the fuel system. According to studies, with increasing vehicle mileage, the amounts of CO and HC emissions in both gasoline and CNG vehicles are increased. But in the gasoline type, the slope of increasing these parameters has been evaluated more. Thus, the values of these parameters in 733000 km of CNG vehicles are almost equal to the same parameters in 242000 km of gasoline vehicles, and these values confirm that the pollutants produced by gasoline vehicles during long-term operation can have more effects on the environment. Therefore, by promoting CNG vehicle technology and using more of these vehicles in urban traffic, the amounts of CO and HC pollutants can be significantly reduced in the long-term. This creates healthier air and a cleaner environment.