Combined effects of polyacrylamide and nanomagnetite amendment on soil and water quality, Khorasan Razavi, Iran

Nanotechnology is increasingly being used to remediate polluted soil and water. However, few studies are available assessing the potential of nanoparticles to bind surface particles, decrease erosion, and minimize the loading of water pollutants from agricultural surface discharge. To investigate this potential, we treated in situ field plots with two practical surface application levels of anionic polyacrylamide (PAM only) with and without nanomagnetite (PAM-NM), examined soil physical properties, and evaluated the impact of this amendment on contaminant sorption and soil erosion control. Polyacrylamide and PAM-NM treatments resulted in 32.2 and 151.9 fold reductions in Mn2+, 1.8 and 2.7 fold for PO43--P, and 2.3 and 1.6 fold for NH4+-N, respectively, compared to the control. Thus, we found that the combination of PAM and NM, had an important inhibitory effect on NH4+-N and PO43--P transport from soil-pollutants which can contribute substantially to the eutrophication of surface water bodies. Additionally, since the treatment, especially at a high concentration of NM, was effective at reducing Mn2+ concentrations in the runoff water, the combination of PAM and NM may be important for mitigating potential risks associated with Mn2+ toxicity. Average sediment contents in the runoff monitored during the rainfall simulation were reduced by 3.6 and 4.2 fold for the low and high concentration PAM-NM treatments when compared to a control. This treatment was only slightly less effective than the PAM-only applications (4.9 and 5.9 fold, respectively). We report similar findings for turbidity of the runoff (2.6-3.3 fold for PAM only and 1.8-2.3 fold for PAM-NM) which was caused by the effects of both PAM and NM on the binding of surface particles corresponding to an increase in aggregate size and stability. Findings from this field-based study show that PAM-modified NM adsorbents can be used to both inhibit erosion and control contaminant transport

Geogenic and anthropogenic sources of potentially toxic elements in airborne dust in northeastern Iran

Little attention has been given to the nature and sources of airborne dust affecting northeastern Iran. The objectives of this study were to examine the concentrations of selected potentially toxic elements (i.e., Cr, Cu, Fe, Mn, Ni, Pb, and Zn), distinguish geogenic from anthropogenic sources, and assess the pollution intensity. A total of 600 samples were collected at 50 locations 12 times between May 2014 and April 2015 for fallout rate; 250 of these samples were selected for geochemical analysis. Mean dust concentrations of Cu, Pb, and Zn were found to be higher in autumn compared to spring as well as higher in the most populous cities. Results suggested that Ni, Cr, Mn, and Fe have come from mainly natural geologic sources, while concentrations of Cu, Pb, and Zn in the dust were associated with anthropogenic sources. Enrichment factors showed minimal to significant enrichment for Cu and Pb and moderate to very high enrichment for Cr, Ni, and Zn. The mean geo-accumulation index revealed that the contamination levels for Cu, Pb, and Zn peaked during autumn. In addition to industrial and traffic sources, seasonal differences in meteorological conditions can create frequent and persistent thermal inversions that at ground level can result in increases in Cu, Ni, Pb, and Zn concentrations during autumn. Because of the diversity of geology and terrain in combination with significant seasonal shifts in winds over this region, this study highlights the need to consider both geogenic and anthropogenic sources in evaluating pollution risks in northeastern Iran