Heavy metals and polycyclic aromatic hydrocarbons in surface sediments of Karoon River, Khuzestan Province, Iran.

Karoon is the longest river in Iran and provides water for industries located along its banks, such as metal, petrochemical, and oil industries. It is also the source of drinking water for cities such as Ahwas, Abadan, and Khorramshahr. In this study, 34 and 18 surface sediment samples were collected and analyzed for heavy metals (Al, As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and polycyclic aromatic hydrocarbons (PAHs). The measured concentrations of heavy metals were compared with US EPA sediment quality guidelines, and the results showed that Cu concentration was above the threshold effect level (TEL) in 65.67% of the samples and Hg concentration was above the effect range median (ERM) in some samples. The results revealed that Hg was severely enriched (5 < enrichment factor < 20) and classified in very high ecological risk index category. It is the major metallic contaminant in the study area. The total PAH concentrations ranged from 11.54-117,730 µg/kg, with the mean value of 7034.55 µg/kg dominated by lower molecular weight (LMW) PAHs. The total potentially carcinogenic PAHs (∑cPAHs) in sediment samples ranged from 2.09 to 31,930 µg/kg, indicating high carcinogenic potential of sediments in the study area. The total toxic equivalent (TEQ) values ranged from 1.06 to 7228.7 µg/kg. Maximum TEQ occurred in Abadan oil refinery station followed by Khorramshahr soap factory and Abadan petrochemical complex. Principal component analysis and cluster analysis also revealed the relationships between the studied parameters and identified their probable sources.

Macronutrients and trace metals in soil and food crops of Isfahan Province, Iran.

The distribution of 10 macronutrients and trace metals in the arable soils of Isfahan Province, their phytoavailability, and associated health risks were investigated; 134 plant and 114 soil samples (from 114 crop fields) were collected and analyzed at harvesting time. Calculation of the soil pollution index (SPI) revealed that arable soil polluted by metals was more severe in the north and southwest of the study area. The results of cluster analysis indicated that Pb, Zn, and Cu share a similar origin from industries and traffic. The concentrations of macronutrients and trace metals in the sampled crops were found in the order of K > Ca > S > Mg > P and Fe > Mn > Zn > Cu > Pb, respectively, whereas calculation of the bioconcentration factor (BCF) indicated that the accumulation of the investigated elements in crops was generally in the order of S ≈ K > P > Mg > Ca and Zn > Cu > Mn > Pb > Fe, respectively. Thus, various parameters including crop species and the physical, chemical, and biological properties of soil also affected the bioavailability of the elements besides the total element contents in soil. Daily intake (DI) values of elements were lower than the recommended daily intake (RDI) levels in rice grains except for Fe and Mn, but for wheat grains, all elements displayed DI values higher than the RDI. Moreover, based on the hazard index (HI) values, inhabitants are experiencing a significant potential health risk solely due to the consumption of wheat and rice grains (particularly wheat grains). Mn health quotient (HQ) also indicated a high risk of Mn absorption for crop consumer inhabitants.