Black carbon (BC) aerosol has been identified as one of key factors responsible for air quality in Beijing. BC emissions abatement could help slow regional climate change while providing benefits for public health. In order to quantify its variations and contribution to air pollution, we systematically studied real-time measurements of equivalent black carbon (eBC) in PM2.5 aerosols at an urban site in Beijing from 2010 to 2014. Equivalent black carbon (eBC) is used instead of black carbon (BC) for data derived from Aethalometer-31 measurement. Equivalent BC concentrations showed significant temporal variations with seasonal mean concentration varying between 2.13 and 5.97 μg m−3. The highest concentrations of eBC were found during autumn and winter, and the lowest concentrations occurred in spring. We assessed the temporal variations of eBC concentration during haze days versus non-haze days and found significantly lower eBC fractions in PM2.5 on haze days compared to those on non-haze days. Finally, we observed a clear inverse relationship between eBC and wind speed. Our results show that wind disperses PM2.5 more efficiently than eBC; so, secondary aerosols are not formed to the same degree as primary aerosols over the same transport distance during windy conditions.
The new-type electrolysis-integrated ecological floating beds (EEFBs) were set up to study their water removal ability due to the excellent water treatment capacity of electrolysis, this enhanced EEFBs were made of polyethylene filled with biochar substrate and in middle of the substrate placed the Mg-Al alloy served as anode and graphite served as cathode. the results show that removal rates of total nitrogen (TN), ammonia nitrogen (NH 3-N), total phosphorus (TP) and phosphate (PO 4 3−-P) by the EEFBs increased 53.1%, 96.5%, 76.5% and 74.5%, respectively. The electrolysis reaction was the main pathway for TN and TP removals in the EEFBs. A higher concentration of hydrogen autotrophic denitrification bacteria was recorded in the substrate of the EEFBs than that in the traditional ecological floating beds (EFBs) (p < 0.05), suggesting that the electrolysis may have enhanced the NO 3 −-n removal efficiency of the EEFBs by promoting the growth and reproduce of hydrogen autotrophic denitrification bacteria. The in-situ formation of Mg 2+ and Al 3+ ions from a sacrificial Mg-Al alloy anode, caused po 4 3−-P and other suspended matter flocculation, improved phosphorus removal and simultaneously reduced turbidity. Thus, electrolysis-integrated ecological floating bed has high nitrogen and phosphorus removal potential in eutrophic water. Eutrophication has become a serious matter of concern in aquatic ecological research, widespread occurrence of water eutrophication results in the loss of ecological integrity, a decreased aquatic biodiversity, the disappearance of submerged vegetation, and the potential production of toxins 1. Diffuse nitrogen (N) and phosphorus (P) pollution are currently the main drivers of eutrophication 2. Ecological restoration technology, such as ecological floating beds (EFBs) have the unique advantage of occupying no land area, operate at low cost, and require simple maintenance; therefore, the EFBs have been widely used as an in-situ ecological remediation technology for treating surface water 3,4. However, problems of seasonal and anaerobic environment constraints on macrophytes and microbes growth, the limited standing biomass 5-7 , decrease of adsorption capacity of substrate 7-11 and the larger cover area 4 usually restrict the usage of EFBs. Thus, the enhanced EFBs which have a long term stable removal capacity needed to be researched. When used, electrolysis in eutrophic water bodies can simultaneously promote heterotrophic denitrifier' growth and reproduce to enhance NO 3 −-N removal 12-15 and to enhance PO 4 3−-P removal through sacrificial anode which can be used as the source of the coagulating ions 16,17. Some researchers were already using electrolysis reaction in constructed wetlands (CWs) and biofilter to intensify N and P removal since the anode was Fe or Al 18-22. When the anode was Fe which could produce Fe 2+ and Fe 3+ ions during the electrolysis process and Fe(III) oxide generated as the end result. Fe(III) oxide has a reddish-brown color and is often called rust which affec...
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