جستجوی مقالات مرتبط با کلیدواژه « background concentration » در نشریات گروه « آب و خاک »

In the world, attention to the content of heavy metals in the soil has increased due to their potential risks to the environment and human health. In recent decades, many studies have been reported on soil contamination by heavy metals in Iran, but most studies do not show heavy metal status in soils on a national scale. On the other hand, despite the importance of background concentration of heavy metals for the assessment of pollution and environmental risks of these metals, no study has yet been published for soils of Iran at the national scale. In this study, an attempt was made to provide a comprehensive understanding of the status of heavy metals in soils of Iran on a national scale based on quantitative and qualitative analysis of the results of studies reported. To conduct this research, a total of 247 studies (both articles and final reports of research projects on field monitoring of heavy metals in soils of Iran that were published until November 2021 were collected. The required information (analysis results of about 21,400 soil samples) were extracted from the studies and first evaluated in terms of quality assurance and quality control criteria. Then, studies were classified into agricultural, urban and industrial based on the type of land use, and after screening and selecting studies that had the minimums required in terms of quality control, various statistics such as weighted average, median, background concentration and pollution index for heavy metals As, Pb, Cd, Cr, Co, Ni, Cu and Zn were calculated and analyzed....

The study area is about 2000 km2 which is important in terms of agriculture, industry and residential complexes. For the purpose of evaluation, 241 samples of surface soil were taken based on systematic nested method from the land soils in the depth of 0 to 10 cm that were under agriculture, pasture and urban uses. The total concentrations of heavy metals of the samples were determined by an atomic absorption spectrometer following the extraction with 5N nitric acid. The results showed that the total amounts of lead, zinc, cadmium and copper in the soil of the studied area were 1.6, 2.0, 4.0, and 1.5 times higher than those in the soil of the natural background respectively. The total concentrations of iron, manganese, chromium, cobalt and nickel in samples were less than those in the background soil. Based on the contamination factor, in the most of samples, concentration of the iron, manganese, chromium, cobalt, nickel and copper were in low to moderate and Pb concentration in 10% of the samples was in high contaminated classes. More than 40 percent of the area was highly polluted with Cd. High levels of contamination factor for lead, zinc, cadmium and copper (Group I) were found in urban land area and contaminated soils with iron, manganese, chromium, cobalt, and nickel (Group II) were observed in agricultural and pasture lands. Overlaying the maps of contamination factors with those of land uses showed that the first group of heavy metals were mostly affected by human activities and the second group by parent materials.