The present study investigates the accumulation of vanadium, iron, and nickel in different depths of soil in collection sites of oil sludge, in Masjed Soleyman Oil and Gas Exploitation Company, located in Choob Sorkh Region. To conduct the research, four sampling points have been selected at the mentioned site, with one sampling point chosen outside the site, as the clean area. Soil sampling has been carried out at depths of 50 and 100 cm, using an auger. All samples are measured to evaluate heavy metals, according to the standard method of Inductive Coupled Plasma (ICP) spectroscopy. The parameters of pH, EC, density, and organic compounds have also been measured. Results have shown that EC, TOM, and density of the soil in the collection site of oil sludge were relatively higher than the reference site. In addition, statistical analysis has shown that electrical conductivity and organic compounds were influenced by the discharge of oil sludge. The mean concentrations of Ni, V, and Fe in both depths (50 cm and 100 cm) of the four studied plots were 68.8 mg/kg, 46.3 mg/kg, and 53565 mg/kg, respectively, indicating that Ni concentration is more than the acceptable limits in the soil. Although, the amounts of V (36.3 mg/kg), Ni (62 mg/kg), and Fe (19416 mg/kg) in the reference site were lower than the studied oil sludge accumulation site. Thus the study area is a place for the accumulation of oil sludge, since the high concentration of heavy metals can be attributed to human interference.

For the first time, the present study removes ions of mercury, in the form of Hg (I) and Hg (II) ions, from aqueous solutions by adsorbing them onto titanium dioxide nanoparticles. The effects of various parameters, such as solution's initial pH, temperature, sorbent dosage, initial mercury concentration, and contact time have been examined on the adsorption process. The experimental results have been compared with Langmuir, Freundlich, and Temkin adsorption isotherms. The maximum adsorption, obtained for Hg (I) and Hg (II) ions, have been 97.5% and 98.6%, respectively. Also, it has been shown that the Langmuir isotherm has better fitting with the equilibrium data than the Freundlich and Temkin isotherms. Thermodynamic parameters of the adsorption, such as and  have been calculated, the negative values of which show that the mercury ions adsorption is an exothermic process and that randomness is decreased, respectively. The study of adsorption kinetics shows that the adsorption of Hg (I) and (II) ions with TiO2 nanoparticles is pseudo-second order.

Water and sediment samples were collected from six different stations, located along the Nil River between February and June 2015. Concentrations of cadmium, lead, zinc, and copper were determined. The extent of the sediment pollution was assessed, using the multiple pollution indices, namely contamination factor (CF), pollution load index (PLI), and the geoaccumulation index (Igeo). The results showed that the level of metals in water samples exceeded background concentrations for Cd and Pb, and the average values for those elements were higher than those of Zn and Cu, ranked as the following: Pb (0.58)> Zn (0.38)> Cd (0.32)> Cu (0.061). For sedimentary samples, the results showed that Zn and Pb concentrations were greater than the concentrations of Cu and Cd, exceeding the background values (except for Cu). The concentration of the tested heavy metals decreased to the following order: Zn (96.2)> Pb (61.5)> Cu (38.83)> Cd (2.34). The Igeo values revealed that Cd (2.87) and Pb (1.61) had accumulated significantly in the Nil River. Contamination factor (CF) confirmed that the sedimentary samples were moderate to very high in terms of Cd, Pb, and Zn contamination. The Pollution Load Index (PLI) values were above one (>1), indicating an advanced decline of the sediment quality. Also, the results showed that the stations, located at the middle portion of the river (S3, S4, and S5) have higher levels of metals than the other stations (S1, S2, and S6). The assessment of heavy metals' levels in water and sedimentary samples indicated that river water and the sediments in the study area were strongly impacted by agricultural activities and domestic waste water.

Increasing consumption of chicken products in Iran makes it very important to analyze their residual heavy metal contents; therefore, the present study has been conducted to determine Pb, Cd, Cr, and Cu in commercial hen eggs, marketed in the city of Hamedan in 2016. In this descriptive study, a sum of 27 samples of hen eggs has been collected from the Hamedan City's market. After preparation and processing the samples in the laboratory, the concentration of metals has been determined in mixed albumen and yolk, using inductively coupled plasma-optical emission spectrometry. Also, all statistical analyses have been conducted, using the SPSS statistical package (version 20) with the results showing that the mean concentrations (mg/kg) of Pb, Cd, Cr, and Cu in the samples have been 0.29±0.16, 0.18±0.04, 0.31±0.03, and 2.81±1.56, respectively. Also, the mean contents of Cd and Cr have surpassed the maximum permissible levels (MPL), established by WHO/FAO. The computed health risk index values show that there is no potential risk for adults and children through egg consumption at the current rate in the study area.According to the results, considering the mean contents of Cd and Cr observed in egg samples have been higher than the MPL; therefore, it is recommended to pay serious attention to pollutants discharge in the environment and monitor chemical residue, especially heavy metals, in the foodstuff.

As an emerging contaminant, 1-H-benzotriazole (1H-BTR) has been detected in the engineered and natural aquatic environments, which usually coexists with heavy metals and causes combined pollution. In the present study, wild-type and transgenic zebrafish Danio rerio were used to explore the acute toxicity as well as the single and joint hepatotoxicity of cadmium (Cd) and 1H-BTR. Although the acute toxicity of 1H-BTR to zebrafish was low, increased expression of liver-specific fatty acid binding protein was observed in transgenic zebrafish when the embryos were exposed to 5.0 μM of 1H-BTR for 30 days. Besides, co-exposure to 1H-BTR not only reduced the acute toxic effects induced by Cd, but also alleviated the Cd-induced liver atrophy in transgenic fish. Correspondingly, effects of combined exposure to 1H-BTR on the Cd-induced expressions of several signal pathway-related genes and superoxide dismutase and glutathione-s-transferase proteins were studied. Based on the determination of Cd bioaccumulation in fish and the complexing stability constant (β) of Cd-BTR complex in solution, the detoxification mechanism of co-existing 1H-BTR on Cd to the zebrafish was discussed.

Child labor is a major challenge in the developing countries and comprehensive health hazard identification studies on this issue are still lacking. Therefore, the current study is an effort to highlight the health concerns of child labor exposed in the key small scale industries of Sialkot, Pakistan. Our findings revealed jolting levels of heavy metals in the urine, blood, serum, saliva, and hair samples collected from the exposed children. For example, in the urine samples, Cd, Cr, Ni, and Pb were measured at the respective concentrations of 39.17, 62.02, 11.94 and 10.53 μg/L in the surgical industries, and 2.10, 4.41, 1.04 and 5.35 μg/L in the leather industries. In addition, source apportionment revealed polishing, cutting, and welding sections in the surgical industries and surface coating, crusting, and stitching sections in the leather industries were the highest contributors of heavy metals in the bio-matrices of the exposed children, implying the dusty, unhygienic, and unhealthy indoor working conditions. Further, among all the bio-matrices, the hair samples expressed the highest bioaccumulation factor for heavy metals. In accordance with the heavy metal levels reported in the exposed children, higher oxidative stress was found in the children working in the surgical industries than those from the leather industries. Moreover, among heavy metals’ exposure pathways, inhalation of industrial dust was identified as the primary route of exposure followed by the ingestion and dermal contact. Consequently, chemical daily intake (CDI), carcinogenic and non-carcinogenic hazard quotients (HQs) of heavy metals were also reported higher in the exposed children and were also alarmingly higher than the corresponding US EPA threshold limits. Taken all together, children were facing serious health implications in these industries and need immediate protective measures to remediate the current situation.

In this research, adsorption of Cu(II) and Cd(II) by biochars was investigated. To enhance the adsorption of these two metal ions, a simple modification of biochars by phosphoric acid (H(3)PO(4)) was carried out. The surface area was larger and the contents of oxygen-containing functional groups of modified biochars were more than pristine biochars. In comparison with pristine biochar, modified biochars sorbed Cu(II) and Cd(II) much more strongly. Surface area had significant effects on the sorption of Cu(II) and Cd(II) by modified biochars. X-ray photoelectron spectroscopy analyses indicated that the quantities of carboxyl (-COOH) and hydroxyl (-OH) functional groups of modified biochars were larger than those of pristine biochar at the same pyrolysis temperature. Compared with that of pristine biochars, the strong ability of -COOH and -OH of modified biochars to form complexes with Cu(II)/Cd(II) ions resulted in higher adsorption of these two metal ions. The phosphorus-containing groups of modified biochars, such as P=O and P=OOH from the result of Fourier transform infrared spectroscopy, interacted and also formed complexes with metal ions, possibly resulting in the enhanced adsorption of Cu(II) and Cd(II). Thus, sorption of metal ions by modified biochars was controlled by the mechanism of surface complexation between oxygen containing functional groups and metals. In general, the H(3)PO(4) modification was an effective method that prepared biochars with a high affinity for the sorption of heavy metals.

Urban road stormwater is an alternative water resource to mitigate water shortage issues in the worldwide. Heavy metals deposited (build-up) on urban road surface can enter road stormwater runoff, undermining stormwater reuse safety. As heavy metal build-up loads perform high variabilities in terms of spatial distribution and is strongly influenced by surrounding land uses, it is essential to develop an approach to identify hot-spots where stormwater runoff could include high heavy metal concentrations and hence cannot be reused if it is not properly treated. This study developed a robust modelling approach to estimating heavy metal build-up loads on urban roads using land use fractions (representing percentages of land uses within a given area) by an artificial neural network (ANN) model technique. Based on the modelling results, a series of heavy metal load spatial distribution maps and a comprehensive ecological risk map were generated. These maps provided a visualization platform to identify priority areas where the stormwater can be safely reused. Additionally, these maps can be utilized as an urban land use planning tool in the context of effective stormwater reuse strategy implementation.

Urban greenspaces provide ecosystem services like more natural ecosystems do. For instance, vegetation modifies soil properties, including pH and soil organic matter content, yet little is known about its effect on metals. We investigated whether the accumulation and mobility of heavy metals, nutrients and carbon is affected by plant functional types (evergreen or deciduous trees, lawns) in urban parks of varying ages in southern Finland. Plant types modified soil physico-chemical parameters differently, resulting in diverging accumulation and mobility of metals and other elements in park soils. However, the effects of plant functional type depended on park age: lawns in parks of ca. 50 y old had the highest contents of Cr, Cu, Fe, Mn, Ni, and Zn, and in these, and older parks (>100 y old), contents of most metals were lowest under evergreen trees. The mobility of metals and other elements was influenced by the amount of water leached through the soils, highlighting the importance of vegetation on hydrology. Soils under evergreen trees in young parks and lawns in intermediately-aged parks were most permeable to water, and thus had high loads of Ca, Cr, Cu, Fe, Ni, tot-P and tot-N. The loads/concentrations of elements in the leachates was not clearly reflected by their content/concentration in the soil, alluding to the storage capacity of these elements in urban park soils. Our results suggest that in urban systems with a high proportion of impermeable surfaces, park soil has the potential to store nutrients and metals and provide an important ecosystem service particularly in polluted cities.

Metal detoxification in plants is a complex process that involves different mechanisms, such as the retention of metals to the cell wall and their chelation and subsequent compartmentalization in plant vacuoles. In order to identify the mechanisms involved in metal accumulation and tolerance in Betula pubescens, as well as the role of mycorrhization in these processes, mycorrhizal and non-mycorrhizal plants were grown in two industrial soils with contrasting concentrations of heavy metals.Mycorrhization increased metal uptake at low metal concentrations in the soil and reduced it at high metal concentrations, which led to an enhanced growth and biomass production of the host when growing in the most polluted soil. Our results suggest that the sequestration on the cell wall is the main detoxification mechanism in white birch exposed to acute chronic metal-stress, while phytochelatins play a role mitigating metal toxicity inside the cells. Given its high Mn and Zn root-to-shoot translocation rate, Betula pubescens is a very promising species for the phytoremediation of soils polluted with these metals.