Maliheh Jamali; Javad Bayat; Seyed Mohammad Reza Talakesh; Seyed Hossein Hashemi
Abstract
Introduction: As a result of human development and population growth, there is a corresponding need for essential resources for humans. Industrial and agricultural activities have greatly polluted most agricultural lands. Petroleum compounds and heavy metals, both are common pollutants of soils that ...
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Introduction: As a result of human development and population growth, there is a corresponding need for essential resources for humans. Industrial and agricultural activities have greatly polluted most agricultural lands. Petroleum compounds and heavy metals, both are common pollutants of soils that have been irrigated by untreated wastewater, which pose a potential threat to the environment. Soil pollution of the agricultural lands will lead to a decline in cultivation and finally decrease food production. Agricultural lands in the southern part of Tehran are being irrigated with untreated wastewater for more than 30 years to produce a variety of vegetables, legumes, and cereals.Material and methods: In this study, the concentration of heavy metals and petroleum compounds were determined in 83 sampling points at two depths (0 to 30 and 30 to 60 cm). The study area was divided into two separate zones, in which 44 points were located in zone 2 and 39 points were located in zone 1. Petroleum hydrocarbons and heavy metals, As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn, were measured at the top and subsoil by MOOPAM and ICP-AES methods, respectively. ArcGIS and R software were applied to create distribution maps of the pollutants and some statistical analyses.Results and discussion: The results showed that the soil of agricultural land in the area is highly polluted, as the concentration of Cr, Pb, Co, and Ni has exceeded the standard level e.g. 0.22 mg/kg for Cd and 620 mg/kg for Pb. The concentration of petroleum compounds in wastewater irrigated lands in both top and subsoil was higher than that of groundwater irrigated lands. High levels of As, Cr, Cu, Pb, and Zn were observed in groundwater irrigated lands compared with wastewater irrigated lands. Cr and Pb were almost 89 and 8 times higher than the standard limit of agricultural lands in Iran, respectively. The spatial distribution map of petroleum compounds showed that only the southeast of the area falls into the heavily contaminated class. The distribution map of heavy metals also revealed that most parts of the studied area fall into the heavily contaminated class. Soil organic matter has more concentration in the topsoil.Conclusion: Overall, the south of the studied area has been more affected by wastewater irrigation, agrochemicals and groundwater pollution in terms of heavy metals and petroleum compounds. Our study revealed various anthropogenic pollution sources, which are mostly from wastewater irrigation and the application of agrochemicals. Therefore, a management plan should be applied to the agricultural lands of this region to control and reduce the level of contamination.
Fatemeh Effati; Javad Bayat; Maryam Rouhi Kerigh; Masoume Mollaei
Abstract
Introduction: In recent years, urban development, population growth, and increasing human activities created many problems in the aquatic resources in urban areas. Awareness of the quality of water has great importance due to the increasing need for drinking water in the metropolitan cities. In this ...
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Introduction: In recent years, urban development, population growth, and increasing human activities created many problems in the aquatic resources in urban areas. Awareness of the quality of water has great importance due to the increasing need for drinking water in the metropolitan cities. In this study water quality variables were examined to determine the quality of grounwater and the risk of toxic and conventional pollutants in terms of human consumption. Material and methods: For this purpose, a number of nine wells were selected to investigate the groundwater quality in ward 10 of the municipality of Tehran in the years 2014 and 2016, in the summer and winter. The physical variables including temperature, color, turbidity, and salinity and chemical variables including dissolved oxygen (DO), pH, electrical conductivity (EC), total suspended solids (TSS), total dissolved solids (TDS), nitrite (NO2-), nitrate (NO3-), ammonium (NH4+), total phosphorus (TP), total nitrogen (TN), sodium (Na), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), lead (Pb), cobalt (Co), zinc (Zn), and detergent as well as microbial variables were measured. Results and discussion: The results showed that due to the presence of coliform bacteria and high levels of NO3-, the groundwater was polluted by human or animal wastewaters, but there was no serious problem, and it was possible to improve the water quality by processes such as chlorine disinfection. Among the physical variables, only the turbidity was almost twice the standard level in some wells. The Analyses of heavy metals showed that the concentrations of Pb, Zn, Fe, and Cu in the groundwater were extremely high, being several times higher than the reported standard level. Changes in TP were very high and reported up to 0.21 mg. Although total coliform and fecal coliform were low, they violated the EPA standard for drinking water. The presence of these two variables in the groundwater is an indication of the penetration of human or animal wastes into the groundwater and, if used, it will cause harmful effects on the health of at-risk people. The total hardness also did not have many fluctuations with a maximum value of 390 mg, which seems fairly favorable, since a concentration of 300 mg is optimal for this variable, and 600 mg is the maximum total hardness of drinking water. The interpolation maps of the groundwater quality index indicated that in the summer of 2014, most of the districts were considered to be in bad and medium conditions, but in the winter of the same year, the conditions changed to medium and relatively good. The water quality index for toxic pollutants in the mentioned seasons and years was in good and very good levels, indicating the groundwater was not polluted by the toxic variables used to determine the index. Conclusion: The reported data for physiochemical and microbial variables showed that the groundwater in the study area had not serious problems, and only the water turbidity exceeded the standard level. Using chlorine disinfection processes to eliminate coliform bacteria and treatments to reduce water turbidity seem to improve water quality. The calculated groundwater indices for the district water indicated that most of the ward, in terms of conventional pollutants, was in the bad-to-medium category in 2014, while in 2016, the quality category changed to medium to fairly good.
