Characterization of silver release from commercially available functional (nano)textiles

Silver, both in the nano as well as in other forms, is used in many applications including antimicrobial textiles. Washing of such textiles has already been identified as an important process that results in the release of silver into wastewater. This study thus investigated the release of silver from eight different commercially available silver-textiles during a washing and rinsing cycle. The silver released was size-fractionated and characterized using electron microscopy. In addition, the antimicrobial functionality of the textiles was tested before and after washing. Three of the textiles contained nanosized silver (labeled or confirmed by manufacturers’ information), another used a metallic silver wire and four contained silver in undeclared form. The initial silver content of the textiles was between 1.5 and 2925 mg Ag/kg. Only four of the investigated textiles leached detectable amounts of silver, of which 34-80% was in the form of particles larger than 450 nm. Microscopic analysis of the particles released in the washing solutions identified Ti/Si-AgCl nanocomposites, AgCl nanoparticles, large AgCl particles, nanosilver sulfide and metallic nano-Ag, respectively. The nanoparticles were mainly found in highly agglomerated form. The identified nanotextiles showed the highest antimicrobial activity, whereas some of the other textiles, e.g. the one with a silver wire and the one with the lowest silver content, did not reduce the growth of bacteria at all. The results show that different silver textiles release different forms of silver during washing and that among the textiles investigated AgCl was the most frequently observed chemical form in the washwater.     

Biotransformation of atrazine and metolachlor within soil profile and changes in microbial communities

Biotransformation studies of atrazine, metolachlor and evolution of their metabolites were carried out in soils and subsoils of Northern Greece. Trace atrazine, its metabolites and metolachlor residues were detected in field soil samples 1 year after their application. The biotransformation rates of atrazine were higher in soils and subsoils of field previously exposed to atrazine (maize field sites) than in respective layers of the field margin. The DT₅₀ values of atrazine ranged from 5 to 18 d in the surface layers of the adapted soils. DT₅₀ values of atrazine increased as the soil depth increased reaching the value of 43 d in the 80-110 cm depth layer of adapted soils. Metolachlor degraded at slower rates than atrazine in surface soils, subsoils of field and field margins with the respective DT₅₀ values ranging from 56 to 72 d in surface soils and from 165 to 186 d in subsoils. Hydroxyatrazine was the most frequently detected metabolite of atrazine. The maximum concentrations of metolachlor-OXA and metolachlor-ESA were detected in the soil layers of 20-40 cm depth after 90 d of incubation. Principal Component Analysis (PCA) of soil Phospholipid Fatty Acids (PLFAs), fungal/bacterial and Gram-negative/Gram-positive ratios of the PLFA profiles revealed that the higher biotransformation rates of atrazine were simultaneously observed with the abundance of Gram-negative bacteria while the respective rates of metolachlor were observed in soil samples with abundance of fungi.     

Heterogeneous reductive dehalogenation of PCB contaminated transformer oil and brominated diphenyl ethers with zero valent iron

Reductive dechlorination and debromination of halogenated biphenyls (PCBs) and diphenyl ethers (PBDEs) occurs efficiently at moderately elevated temperatures (350-600 °C) with zero valent iron (iron powder) in a nitrogen atmosphere. The proton donors tested were waste transformer oil, iso-octane, and n-decane. Observation of production of biphenyl and diphenyl ether and their condensation products indicates that the reaction is not simple pyrolysis, but a reduction. No halogenated organic products are observed.     

Phytoremediation of textile effluent and mixture of structurally different dyes by Glandularia pulchella (Sweet) Tronc

Plants of Glandularia pulchella (Sweet) Tronc. performed decolorization of structurally different dyes to varying extent because of induction of different set of enzymes in response to specific dyes. Differential pattern of enzyme induction with respect to time was obtained for lignin peroxidase, veratryl alcohol oxidase, tyrosinase and dichlorophenolindophenol reductase during the decolorization of dye mixture, whose combined action resulted in greater and faster decolorization of dyes. HPLC, FTIR and High Performance Thin Layer Chromatography (HPTLC) analysis confirmed degradation of dyes from textile effluent and mixture. HPTLC demonstrated progressive decolorization of dye mixture along with preferential degradation of the dyes. G. pulchella showed reduction in American Dye Manufacturer's Institute from 405 to 21 and 418 to 22, in case of textile effluent and mixture of dyes respectively. The non-toxic nature of the metabolites of degraded textile dye effluent and mixture of dyes was revealed by phytotoxicity studies.     

Comparison of homologous and heterologous formats in nanocolloidal gold-based immunoassays for parathion residue determination

The effectiveness of homologous and heterologous formats in a nanocolloidal gold-based immunoassay for pesticide residue determination was investigated. Parathion, one of the most toxic organophosphorus pesticides, was used as the target analyte. One-step homologous and heterologous test strips based on a nanocolloidal gold-labeled monoclonal antibody were developed for the rapid detection of parathion residues. The results showed that the heterologous format was more effective than the homologous format, being more sensitive, more specific to parathion and more tolerant of matrix interferences. The best competitive hapten was found to have a moderate heterology and the opposite electronic distribution to the immunizing hapten. The detection limits for parathion using the preferred heterologous strip were 1 μg/L in water samples and 5 μg/kg in soil and food samples.     

Metal stress and decreased tree growth in response to biosolids application in greenhouse seedlings and in situ Douglas-fir stands

To assess physiological impacts of biosolids on trees, metal contaminants and phytochelatins were measured in Douglas-fir stands amended with biosolids in 1982. A subsequent greenhouse study compared these same soils to soils amended with fresh wastewater treatment plant biosolids. Biosolids-amended field soils had significantly higher organic matter, lower pH, and elevated metals even after 25 years. In the field study, no beneficial growth effects were detected in biosolids-amended stands and in the greenhouse study both fresh and historic biosolids amendments resulted in lower seedling growth rates. Phytochelatins - bioindicators of intracellular metal stress - were elevated in foliage of biosolids-amended stands, and significantly higher in roots of seedlings grown with fresh biosolids. These results demonstrate that biosolids amendments have short- and long-term negative effects that may counteract the expected tree growth benefits.     

Assessment of exposure to DDT and metabolites after indoor residual spraying through the analysis of thatch material from rural African dwellings

Introduction  

We report on the analysis of 4,4′-dichlorodiphenyltrichloroethane (4,4′-DDT) and its metabolites in thatch and branch samples constituting the wall materials of dwellings from South African subtropical areas. This approach was used to assess the exposure to DDT in the residents of the dwellings after indoor residual spraying (IRS) following recommended sanitation practices against malaria vectors.     

Fallout traces of the Fukushima NPP accident in southern West Siberia (Novosibirsk,Russia)

Background  

The fallout of artificially produced radioactive isotopes has been recorded at a site in southern West Siberia (54°50′43.6″ N, 083°06′22.4″ E, Novosibirsk, Russia).     

Assessment of heterogeneity of metal composition of fine particulate matter collected from eight U.S. counties using principal component analysis

The main objectives of this study are to (1) characterize chemical constituents of particulate matter (PM) and (2) compare overall differences in PM collected from eight US. counties. This project was undertaken as a part of a larger research program conducted by the Johns Hopkins Particulate Matter Research Center (JHPMRC). The goal of the JHPMRC is to explore the relationship between health effects and exposure to ambient PM of differing composition. The JHPMRC collected weekly filter-based ambient fine particle samples from eight US. counties between January 2008 and January 2010. Each sampling effort consisted of a 5-6-week sampling period. Filters were analyzed for 25 metals using inductively coupled plasma mass spectrometry (ICP-MS). Overall compositional differences were ranked by principal component analysis (PCA). The results showed that weekly concentrations of each element varied 3-40 times between the eight counties. PCA showed that the first five principal components explained 85% of the total variance. The authors found significant overall compositional differences in PM as the average of standardized principal component scores differed between the counties. These findings demonstrate PCA is a useful tool to identify the differences in PM compositional mixtures by county. These differences will be helpful for epidemiological and toxicological studies to help explain why health risks associated with PM exposure are different in locations with similar mass concentrations of PM.