فاکتور آلودگی

River sediments are one of great importance adsorbent of the metallic contaminants. Globally, aquatic ecosystems are highly polluted with heavy metals arising from anthropogenic and terrigenous sources. The objective of this study was to investigate the geochemical pollution of metal contaminations in stream sediments and it,s possible sources of in Pole-rud in easthern of Guilan province pollutants. Collected stream sediments were analysed for heavy metal concentration with ICP method. The degree of pollution in Pole-rud stream sediments for lead, Nickel, zinc, Cobalt, chromium, titanium and vanadium was assessed using geoaccumulation (Igeo) index and contamination factor (CF). The results indicated that: (1) the calculation of geo-accumulation index suggest that Pole-rud stream sediments have relatively high polluted index for lead element and moderately polluted for Cobalt and chromium; (2) contamination factor for lead and aluminum are very high contamination, for, Cobalt, chromium, titanium and vanadium are moderate contamination and for zinc is low contamination; (3) the sediments have been polluted with lead and aluminum have high anthropogenic influences; (4) Cobalt and chromium elements indicate terrigenous sources.

Every year a great deal of chemical fertilizers, pesticides and sewage sludge used in agriculture soils; this may cause the increase in concentration of Soil heavy metals. The purpose of this study was to investigate the effects of assessment of agriculture activities on accumulation of Cadmium, Cobalt and Chromium; and determines the trend of heavy metal accumulation in soil.

To achieve this purpose 97 soil samples were taken from different agriculture fields with different cultivation archaism in Hamedan province in western IRAN by systematic approach. ANOVA test has been used to compare the concentration of heavy metals in different farms, the trend of accumulation heavy metals obtained in regards to cultivation archaism and the mean of metals concentration in different cultivations. Moreover, contamination Factor Index has been used for comparison of contamination risk in cultivations with various archaisms.

Mean concentrations in 20-, 35- and 65-year-old cultures for cadmium metal were 0.14, 0.16 and 0.19, respectively, for cobalt metal, 17/94, 18/05 and 79/20, respectively and for chromium metal 58.89, 72.99 and 88.09 mg / kg, respectively. The results showed that the longevity of cultivation affected on heavy metal accumulation in soil. The trend of Cd, Co and Cr accumulation in soil was exponential.

Due to the fact that agricultural soils are one of the important routes for the transfer of heavy metals to the human food chain, it is necessary to monitor soils that are potentially exposed to toxic metals.

The purpose of this research is to investigate the distribution of heavy metals and evaluating geo-accumulation and contamination factors on these elements in the stream sediments of Shourab Kashmar area. There are indications of some elements such as Mercury, Lead, Iron, and Copper that might be the cause for environmental pollution in this area.

After processing of satellite images and performing geological studies, 21 samples of stream sediments were gathered. By determining the salinity, pH, and EC parameters as well as the soil texture of samples, 14 samples were tested in order to study the concentration of heavy metals with the ICP-OS systems in the ZarAzma Laboratory. The collected results were processed and studied using GIS, SPSS, and Excel software.

With the exception of the Silver, Copper, Cadmium, Cobalt, Chromium, and Nickel elements which show some level of contamination, there is no evidence of environmental pollution, in the stream sediments in this area. The amount of pH from 7.5 to 8.2 and EC from 0.3 µs/cm to 5 µs/cm and salinity from 150 to 2500 are varying.

There is a similarity between the distribution of the Nickel, Cobalt, and to some degrees, Chromium in the stream sediments of the study area. This can be related to the volcanic rocks which are mainly intermediate in composition. The Lead and Zinc are mainly concentrated on the north and some towards east of the area, and the Arsenic and Antimony elements in the north and north-west of the study area. The origin of these elements could be connected to mineralization in this area, which has not been focused on so far.

Heavy metals are a global problem; their entrance to the human food chain bring about irreparable problems. These metals are naturally occurring in rocks and soils, but the release of metals into the soil has increased through human activity over the past decade. The purpose of this study was to determine the contamination of heavy metals like, lead and chromium in the soil around the Qayen Cement Plant using the geo-accumulation index, pollution factor and pollution index. According to a systematically sampled network at eight different directions in distances of 200, 300, 400, 500, 600, 700, 800 and 1000 meters from the cement factory, totally, 64 samples were taken. Soil samples were passed through a 2-mm sieve, and then digested with hydrofluoric acid, perchloric acid, hydrochloric acid, and nitric acid then the concentration of Pb and Cr was measured using atomic absorption spectrometer (Contr AA700) through flame method. The results suggest that the average metal chromium and lead were 52.05 and 66.79 mg/kg respectively. A Geo-accumulation index value for the metal in all stations at various distances is located in classes I and II (non-polluted to little contaminate). Pollution index values indicate that the stations at various distances, the moderate pollution accounted for 39 and 44% chromium and lead, as well as high pollution as 61 and 56% of these two elements respectively. In conclusion, as the result shows the concentration of Pb and Cr are higher than control samples and are accumulating.

Solid waste is one of the most important sources of soil contamination. Soil chemical contaminants such as heavy metals have created deep concern throughout the world. Heavy metals are naturally present in all soils, but soil contamination due to human activities is increasing. The accumulation of these metals in the soil eventually results in their entry into the food cycle and threaten human health and other living beings. In this study, the soil pollution of Zahedan city landfill by heavy metals was studied using contamination factor index. A total of 20 soil samples, 10 topsoil samples (up to 30 cm) and 10 depth soil samples (from a depth of 30 to 60 cm) were collected from landfill and processed for determination of element concentrations by Atomic Absorption Spectrometry and for statistical analysis, the SPSS software version 23 was used. The results showed that mean concentrations of chromium, cadmium, lead, and arsenic in topsoil were 152.48, 0.213, 54.499, and 0.344 mg/kg respectively while these concentrations for deep soil were 177.14, 0.252, 49.365, 0.414 mg/kg respectively. The contamination factor index confirmed that most of sample stations were in class of low (CF >1 and 1 15≤"> CF >3) to moderate pollution.

Parishan wetland is one of the most valuable and ecologically important ecosystems in the world which has completely dried up in recent years due to successive droughts (Dehghani, 2007). Considering that heavy metals are among the most important pollutants of the environment, their survival time is high in sediments (Ullah et al., 2017). Also, these metals have harmful effects on aquatic ecosystems, and sediments are both a source of and a place to store these elements. Acquiring information about these metals is important (Bhuiyana et al., 2010).

The purpose of this study was to estimate the level of contamination of Perishan wetland sediments with the heavy metals copper, iron, manganese and zinc using the enrichment index, geochemical accumulation index, degree of contamination and the comprehensive pollution factor index. In this study, 40 sediment samples with a weight of 200 g were systematically harvested. After acid digestion and filtering to read the concentration of toxic metals liberated in each sample, an AAS atomic absorption device by the Thermo Company (UK) was used. In this study, because of the lack of any specific standard for soil contamination in our country, standards from other countries were used. The average concentration of the metals studied in the region is lower than the maximum acceptable concentration (mg / kg) for the countries of Poland, Canada and Australia.

The changes in pH and electrical conductivity (Ec) were calculated in the range of 2.7-9.2 and 4.2-34, respectively, and the concentration of heavy metals based on mg/kg was found in most samples including manganese (2.18-3.71), iron (3.6-4.26), zinc (2.15-8.3) and copper (5.3-8.13), respectively. The background concentration for manganese, copper, iron and zinc was 950, 50, 41000 and 75 mg/kg, respectively. The geochemical accumulation index, the pollution factor and the comprehensive pollution factor
index were all used to determine contamination levels in the area. The geochemical accumulation index was less than zero for all metals, which shows the non-contamination class of the area. In addition, the factor of contamination index for most of the samples was in the class unpolluted, and the contamination factor for all metals was less than one, so that all data were placed in the non-contaminated class. The results also showed that the elements of manganese, copper, iron and zinc have a geological and agricultural origin, while the concentration of metals in the soil was related to their natural origin.

Finally, it can be stated that the studied area has the lowest risk of contamination with heavy metals. In fact, it can be said that the copper, iron, manganese and zinc found in this region have a geological origin and they change through the natural processes of geology and through springs in the wetland.

Any change in the environmental characteristics such that the normal functions and biological balances are disrupted and life of organisms is threatened directly or indirectly is called environmental pollution. The purpose of this study was to determine the contamination with heavy metals Chromium, Copper, Nickel and Zinc in soils of Nahavand city, Hamadan Province using different indicators. A total of 39 soil samples were taken systematically and concentrations of Chromium, Copper, Nickel and Zinc were measured using a spectrophotometer. Geo-accumulation index, contamination actor and Nemero comprehensive pollution index were used to determine the extent of contamination in the study area. Results showed that the Cobalt concentration in the region is at the maximum allowable concentrations based onr other countries. The Geoaccumulation index results showed that the rate of accumulation of the index is between 0 and 1 for all metals. Concentration of heavy metals in soil was related to their natural origin. Contamination factor results showed that most samples were moderately to highly polluted. Contamination factor for Chromium was the highest and 10.26% of the data showed they were moderately to highly polluted. Analysis of interpolation maps of comprehensive pollution index showed that the metals Chromium, Copper, Nickel and Zinc have geological and agricultural origins. These metals are present naturally in soil, but human activity has caused the accumulation of these metals in the soil.