Removal of methyl chloroform in a coastal salt marsh of eastern China

Removal and Oxidation of As(III) from Water Using Iron Oxide Coated CTAB as Adsorbent

Iron oxides such as magnetite and maghemite coated with cetyltrimethylammonium bromide (CTAB) are very promising materials for wastewater treatment because iron oxide can be easily separated from solutions using the magnetic separation procedure Iron oxide (IO) coated CTAB was synthesized by an adapted co-precipitation method. In the present study, the IO-CTAB was used for removing arsenic from water for the first time. In the present study, the performance of iron oxide coated CTAB biocomposites as an adsorbent for arsenic removal from aqueous solutions was examined. X-ray diffraction (XRD) analysis and the results revealed a cubic phase Fd-3 m of Fe₃O₄ with lattice a = 8.40 Å and average crystal size equal to 17.26 ± 3 nm. The mean particle size calculated from transmission electron microscopy (TEM) was 19.86 ±1.7 nm. The results of the adsorption batch experiments and the data determined using the Langmuir and Freundlich models emphasized that IO-CTAB nanoparticles were favorable for the adsorption of As(III) ions from aqueous solutions. Ultrasound measurements have shown that IO-CTAB is a cost-effective biocomposite for removing arsenic from contaminated solutions. Moreover, x-ray photoelectron spectroscopy (XPS) has shown that during the process of arsenic absorption, there is oxidation from As(III) to As(V), which leads to a decrease in toxicity during this process. The results of the cytotoxic assays confirmed that the IO-CTAB nanoparticles did not induce any morphological changes in the HeLa cells and did not affect their proliferation after 24 h of incubation.

Spatial and temporal variations of the greenhouse gas emissions in coastal saline wetlands in southeastern China

Coastal wetlands are crucial to global climate change due to their roles in modulating atmospheric concentrations of greenhouse gases (GHGs) (CO₂, CH₄, N₂O). Under a warming climate, we investigated spatial and temporal variations of GHGs emissions over the coastal wetlands in southeastern China during 2012-2014. Five dominant land cover types in coastal wetlands have been considered, including the bare mud flat (BF), the Spartina alterniflora flats (SAF), the Suaeda glauca flats (SGF), the Phragmites australis flat (PAF), and the Scripus triqueter flat (STF). The results showed that the annual average CO₂ fluxes were 305.8, 588.8, 370.2, and 136.5 mg m^-2 h^-1 from spring to winter. CH₄ fluxes presented to be a sink in spring (- 0.02 mg m^-2 h^-1), and functioned as a source in the following seasons. Correlation analysis indicated that the surface air temperature and the cumulative precipitation could be two main factors that influenced the seasonal and inter-annual variations of GHGs emissions. In addition, we provided a regional budget of GHGs emissions that suggested the variations of GHGs emissions under a warming climate.