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Fu H.,University of Iowa | Fu H.,Center for Global and Regional Environmental Research | Fu H.,Fudan University | Cwiertny D.M.,University of California at Riverside | And 4 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2010

In this study, the photoreductive dissolution of Fe-containing mineral dust particles in acidic media is investigated. Photolysis experiments were performed using a solar simulator to irradiate acidic mineral dust suspensions prepared from source materials of Inland Saudi sand (IS), Saharan sand (SS) and one commercial sample, Arizona test dust (AZTD). The results show that Fe dissolution is a pH-dependent process, and total Fe solubility decreases with the solution pH increasing. Comparing iron dissolution from different source materials, Fe(II)-containing AZTD is more soluble than IS and SS samples, irrespective of the presence or absence of light. Experiments performed at three different temperatures of 278, 293, and 308 K show that both total dissolved Fe and dissolved Fe(II) increase with temperature and upon light exposure. Results of dissolution studies with AZTD performed at low pH also illustrate that the nature of the acid strongly influences iron solubilization. Fe solubility decreases in the suspensions of H2SO4 and HNO3 in the presence of light, whereas Fe solubility increases in the HCl solution under the irradiation compared to the dark reaction. Finally, our results confirm earlier work showing that photoreductive dissolution of Fe is very sensitive to dissolved oxygen. Results from this laboratory study show that mineralogy and speciation of iron, as well as environmentally relevant factors including pH, light, O2, and nature of the inorganic anion, NO 3 -, SO4 2-, and Cl-, must be considered when modeling the input of iron to the oceans. Copyright 2010 by the American Geophysical Union.

News Article | December 21, 2016
Site: www.eurekalert.org

Hydraulic fracturing has boosted U.S. energy production while coming under scrutiny for its potential environmental impacts, mostly related to the wastewater the method generates. Now, a report in the ACS journal Environmental Science & Technology Letters takes a look at solid waste from horizontal gas wells. The study found that some well waste from the Marcellus shale in Pennsylvania contained radioactive material not previously reported, with the potential for leaching from landfills into the environment. Drilling horizontal wells for hydraulic fracturing operations results in a large amount of gooey solid waste, or drill cuttings. In 2011, natural gas exploration and extraction in the Marcellus Shale formation produced an estimated 2.37 million tons of cuttings in Pennsylvania alone with almost all of it ending up in landfills, according to a review published in Environmental Practice. A few studies have found naturally occurring radioactive materials in the solid waste, but the research only focused on several long-lived radioactive isotopes including uranium-238 and radium-226. Andrew W. Nelson and colleagues wanted to investigate whether other radioactive isotopes might be in drill cuttings and whether they could impact the environment. The researchers devised a method to test the drill cuttings from horizontal wells in the Marcellus Shale in Pennsylvania. In addition to uranium-238 and radium-226, the researchers report the samples contained elevated levels of the environmentally persistent radioactive isotopes uranium-234, thorium-230, lead-210 and polonium-210. A simulation of leaching over a range of acidity levels suggested that at low pH, uranium isotopes readily leached from drill cuttings, which raises questions as to whether uranium will seep into the environment from a landfill. Other isotopes appeared less leachable under the conditions tested. Leaching for all radionuclides declined as pH increased. The researchers say that because they were only able to obtain three samples from one well, the findings aren't generalizable. But, they add, their study demonstrates that further testing is needed to understand what is in solid waste from the country's proliferating horizontal wells and whether it might pose any environmental risks. The authors acknowledge funding from the Center for Global and Regional Environmental Research at the University of Iowa. The abstract that accompanies this study is available here. The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With nearly 157,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio. To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.

Mattioli M.,Urbino University | Giordani M.,Urbino University | Dogan M.,Hacettepe University | Dogan M.,Center for Global and Regional Environmental Research | And 5 more authors.
Journal of Hazardous Materials | Year: 2016

Erionite belonging to the zeolite family is a human health-hazard, since it was demonstrated to be carcinogenic. Conversely, offretite family zeolites were suspected carcinogenic. Mineralogical, morphological, chemical, and surface characterizations were performed on two erionites (GF1, MD8) and one offretite (BV12) fibrous samples and, for comparison, one scolecite (SC1) sample. The specific surface area analysis indicated a larger availability of surface sites for the adsorption onto GF1, while SC1 shows the lowest one and the presence of large pores in the poorly fibrous zeolite aggregates. Selected spin probes revealed a high adsorption capacity of GF1 compared to the other zeolites, but the polar/charged interacting sites were well distributed, intercalated by less polar sites (Si-O-Si). MD8 surface is less homogeneous and the polar/charged sites are more interacting and closer to each other compared to GF1. The interacting ability of BV12 surface is much lower than that found for GF1 and MD8 and the probes are trapped in small pores into the fibrous aggregates. In comparison with the other zeolites, the non-carcinogenic SC1 shows a poor interacting ability and a lower surface polarity. These results helped to clarify the chemical properties and the surface interacting ability of these zeolite fibers which may be related to their carcinogenicity. © 2015 Elsevier B.V.

Fu H.,Fudan University | Lin J.,CAS Shanghai Institute of Applied Physics | Shang G.,Fudan University | Dong W.,Fudan University | And 4 more authors.
Environmental Science and Technology | Year: 2012

In this study, iron solubility from six combustion source particles was investigated in acidic media. For comparison, a Chinese loess (CL) dust was also included. The solubility experiments confirmed that iron solubility was highly variable and dependent on particle sources. Under dark and light conditions, the combustion source particles dissolved faster and to a greater extent relative to CL. Oil fly ash (FA) yielded the highest soluble iron as compared to the other samples. Total iron solubility fractions measured in the dark after 12 h ranged between 2.9 and 74.1% of the initial iron content for the combustion-derived particles (Oil FA > biomass burning particles (BP) > coal FA). Ferrous iron represented the dominant soluble form of Fe in the suspensions of straw BP and corn BP, while total dissolved Fe presented mainly as ferric iron in the cases of oil FA, coal FA, and CL. Mössbauer measurements and TEM analysis revealed that Fe in oil FA was commonly presented as nanosized Fe3O4 aggregates and Fe/S-rich particles. Highly labile source of Fe in corn BP could be originated from amorphous Fe form mixed internally with K-rich particles. However, Fe in coal FA was dominated by the more insoluble forms of both Fe-bearing aluminosilicate glass and Fe oxides. The data presented herein showed that iron speciation varies by source and is an important factor controlling iron solubility from these anthropogenic emissions in acidic solutions, suggesting that the variability of iron solubility from combustion-derived particles is related to the inherent character and origin of the aerosols themselves. Such information can be useful in improving our understanding on iron solubility from combustion aerosols when they undergo acidic processing during atmospheric transport. © 2012 American Chemical Society.

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