Fluorescent Visualization of Chemical Profiles across the Air-Water Interface.

Chemical transfer across the air-water interface is one of the most important geochemical processes of global significance. Quantifying such a process has remained extremely challenging due to the lack of suitable technologies to measure chemical diffusion across the air-water microlayer. Herein, we present a fluorescence optical system capable of visualizing the formation of the air-water microlayer with a spatial resolution of 10 µm and quantifying air-water diffusion fluxes using pyrene as a target chemical. We show for the first time that the air-water microlayer is composed of the surface microlayer in water (∼290 ± 40 µm) and a diffusion layer in air (∼350 ± 40 µm) with 1 µg L-1 of pyrene. The diffusion flux of pyrene across the air-water interface is derived from its high-resolution concentration profile without any pre-emptive assumption, which is 2 orders of magnitude lower than those from the conventional method. This system can be expanded to visualize diffusion dynamics of other fluorescent chemicals across the air-water interface and provides a powerful tool for furthering our understanding of air-water mass transfer of organic chemicals related to their global cycling.

Riverine transport dynamics of PBDEs and OPFRs within a typical e-waste recycling zone: Implications for sink-source interconversion.

Despite ample evidence on spreading of e-waste derived hazardous materials, riverine transport of organic contaminants from e-waste recycling zones to surrounding areas has not been evaluated. To address this issue, passive and grab sampling methods were used to assess sediment-water diffusion and horizontal transport of polybrominated diphenyl ethers (PBDEs) and organophosphorus flame retardant (OPFRs) at upstream and downstream sites of two rivers in a typical e-waste recycling zone. Sediment acted as a source of BDE-17 with fluxes of 0.007-0.04 ng m-2 d-1 at all sampling sites. BDE-47 and BDE-99 reached equilibrium between overlying water and sediment porewater. Sediment interconverted from a sink at the upstream site to a source of OPFRs at the downstream site with a flux varying between -7.3 and 234 ng m-2 d-1. The amounts of OPFRs (11-45 g d-1) via horizontal riverine transport were greater than those of PBDEs (0.68-2 g d-1). The vertical sediment-water diffusion of PBDEs and OPFRs was not significant compared to horizontal riverine transport. The annual riverine outputs of PBDEs and OPFRs from the downstream sites were 250-330 g and 12,000-16,500 g, respectively, indicating the significance of riverine transport of organic contaminants from e-waste recycling zones to surrounding areas.

Determination of low-density polyethylene-water partition coefficients for novel halogenated flame retardants with the large volume model and co-solvent model.

The partition coefficient (Kpew) of an analyte between low-density polyethylene (LDPE) film and water is a critical parameter for measuring freely dissolved concentrations of the analyte with PE passive sampling devices. Measuring log Kpew for super hydrophobic organic chemicals (HOCs) have been proven extremely difficult. The present study developed a large volume model for measuring log Kpew of super HOCs, i.e., novel halogenated flame retardants (NHFRs). Results showed that the measured log Kpew values of selected PAHs and PCBs obtained by the large volume model were in line with those from the co-solvent model and the literature data within less 0.3 log units of difference, while those of NHFRs (6.27-7.34) except for hexachlorocyclopentadienyldibromocyclooctane (HCDBCO) and Decabromodiphenyl ethane (DBDPE) were significantly lower than those (6.51-8.89) from the co-solvent model. A curvilinear relationship was observed between log Kpew and log Kow of all target compounds, with the turning point at log Kow = âˆ¼8.0 in the large volume model, but that was not found for the co-solvent model. These can be attributed to the large molecular volumes (> 450 Å3) for NHFRs, which require high Gibbs free energy to penetrate into the inside structures of LDPE in the large volume model. However, the solvent swelling effects in the co-solvent model needs to be investigated. Therefore, the large volume model is robust to determine the Kpew values of super HOCs for facilitating the application of aquatic passive sampling techniques.

Effect of Gan-Pi regulatory needling in treating chloasma.

OBJECTIVE: To study the effect of Gan-Pi regulatory needling (GPRN) in treating chloasma and its influences on female sex hormones, superoxide dismutase (SOD), lipid peroxide (LPO) and melanocyte-stimulating hormone (MSH). METHODS: Ninety chloasma patients were equally randomized to three groups, the treatment group treated with GPRN, the control group treated with conventional Western medicine and the blank group untreated. Changes in the scores of skin lesion (area and color) and symptom, as well as blood levels of female sex hormones, MSH, SOD and LPO were observed and compared after 3 months of treatment. RESULTS: In the treatment group, the scores of skin lesion area and color were reduced from 2.76 + or - 0.96 and 2.48 + or - 0.78 before treatment to 1.42 + or - 0.42 and 1.03 + or - 0.41 after treatment, respectively, while in the control group they were from 2.78 + or - 1.06 and 2.53 + or - 0.88 to 1.58 + or - 1.23 and 1.28 + or - 0.96, respectively, all showing significant changes (P<0.05); the scores were insignificantly changed in the blank group (P>0.05). At the same time, the score of symptoms in the treatment group significantly improved after treatment (P<0.05), significantly different from that of the other two groups. Comparison of female sex hormones among groups showed no significant differences either before or after treatment. The level of LPO decreased and SOD increased in both the treatment group and the control group significantly (all P<0.05), but significant lowering of MSH was only seen in the treatment group (P<0.05). CONCLUSIONS: GPRN can effectively lessen the size and lighten the color of chloasma, improve the accompanying symptoms in patients and decrease LPO and MSH levels and increase the SOD level, but will not affect the level of the female sex hormones.