COMMENT pubs.acs.org/est
Orders of Magnitude in Environmental Chemistry
“N
ano” effects are characterized by size- and shape-dependent physicochemical material properties that can differ significantly from those of the bulk form. Materials science has exploited nano for technologies from (photo)electronics to biomedical diagnoses. That nanomaterials interact with biological entities means environmental chemistry is shot through with nanoscale effects: geosphere and hydrosphere environments are essentially proximal mineral surfaces (bulk and colloidal) with natural/dissolved organic matter (NOM/DOM). As articulated in their Guest Comment (Environ. Sci. Technol. DOI 10.1021/ es2007148) and Feature (Environ. Sci. Technol. DOI 10.1021/ es103992s), Aiken et al. have assembled this Focus Issue on Nanoscale Metal Organic Matter Interaction to illustrate the present state of this interdisciplinary field. The research runs from fundamental studies into natural molecular biogeochemistry to confronting the factors influencing ecotoxicology and public environmental health contexts. Getting numerical models to agree with empirical data for metal organic matter complexation has evolved in the last 30 years. Cabaniss further developed his a priori agent-based quantitative structure property relationship model to address binding site structure. Such models can help track metal cycles in the environment (Environ. Sci. Technol. DOI 10.1021/ es102408w). Arsenic (As) complexes with DOM are attributed with this toxic metal mobilizing in water supplies. The role of iron (Fe) in facilitating As DOM chemistry was investigated by Liu et al. to elucidate the kinetics and stability of As Fe DOM complexes. Understanding Fe As synergies can aid the securing of drinking water sources (Environ. Sci. Technol. DOI 10.1021/es102931p). Precipitation of metals can kinetically result in formation of nanoparticles in addition to sequestered bulk forms. Deonarine et al. explored the interaction of nanoparticulate zinc sulfide (sphalerite, ZnS) and NOM to better understand whether traditional assumptions of toxicity hold under given physicochemical conditions. Such fundamentals of biogeochemistry have a role in the chemistry of metabolism involving metals (Environ. Sci. Technol. DOI 10.1021/es1029798). NOM can increase the mobility of myriad heavy metals including the “rare earth” lanthanides and the actinides which include uranium and transuranic elements like plutonium. Janot et al. exploited the luminescent europium(III) NOM R-alumina (Eu[III] NOM R-Al2O3) system to analogize how (III) actinides mobilize in organic matter/aluminosilicate environments. Such work can aid sequestration of radioactive waste, possibly with clay materials (Environ. Sci. Technol. DOI 10.1021/ es102592a). The presence of Fe-(hydr)oxide nanoparticles in environmental chemistry systems means metal NOM/DOM interactions can have size- and shape-dependent results. Barton et al. investigated the size effects of hematite (R-Fe2O3) on lead(II) (Pb[II]) sorption in the presence of DOM. Such analysis helps fully characterize environmental chemistry fundamentals (Environ. Sci. Technol. DOI 10.1021/es1026135). r 2011 American Chemical Society
Engineered nanoparticles are stabilized in solution via organic “capping” molecules. Stankus et al. investigated how a humic acid system caps gold (Au) nanoparticles under various ionic strengths. Such studies can provide a potential way to track the fate and transport of metals that would otherwise be sequestered in bulk form (Environ. Sci. Technol. DOI 10.1021/es102603p). Nanoparticulate zerovalent iron (nZVI) has been identified as a promising in situ pollution remediation technology. Kadar et al. investigated the toxicity of stabilized nZVI with marine invertebrates. This information helps plan and undertake the cleanup of contaminated sites (Environ. Sci. Technol. DOI 10.1021/ es1029848). Subsurface environments with elevated levels of dissolved organic carbon (DOC) have been correlated with increased mobility of microbial species. Harvey et al. conducted a field study to determine how surfactant DOCs might influence contamination of a sandy aquifer by microbes. Such studies link surface (environmental) chemistry with epidemiology to inform public health plans (Environ. Sci. Technol. DOI 10.1021/ es102989x). Darcy J. Gentleman Managing Editor
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[email protected] Published: April 13, 2011 3193
dx.doi.org/10.1021/es2008243 | Environ. Sci. Technol. 2011, 45, 3193–3193
