Atmospheric Mercury Isotope Shifts in Response to Mercury Emissions from Underground Coal Fires

A MELET- and IFE-based UV-visible luminescent ratiometric probe for quantization of mercury(II) and nitrofurantoin in environmental sewage

A novel fluorimetric ratiometric probe of green and eco-friendily nitrogen-enriched, oxygen-doped carbon nanodots (Cnanodots) was prepared for the quantitative analysis of mercury(II) (HgII) and nitrofurantoin (Nit) in the environmental sewage. The Cnanodots exhibits dual-emission peaks respectively at 345 and 445 nm under 285 nm excitation, with excitation-independent properties. Unexpectedly, this Cnanodots displays two obvious ratiometric responses to HgII and Nit through decreasing the signal at 345 nm and remaining invariable at 445 nm. Experimental results confirm that the highly sensitive analysis of HgII and Nit are achieved respectively based on matching energy-level electron transfer and inner filter effect mechanisms. The fluorescence (FL) ratiometric intensity of [FL345nm/FL445nm] expresses a good linear relationship with the concentration of HgII in the scope of 0.01-20 μM, while the logarithm of [Log(FL0345nm-FL345nm)] on the quenching degree of the probe by Nit also shows a good linear correlation within the range of 0.01-100 μM. The detection limits were calculated to be 4.14 nM for HgII, and 7.84 nM for Nit. Moreover, recovery experiments of Cnanodots for HgII and Nit sensing in real sewage samples obtained satisfactory results, comfirming the feasibility of practical application.

A rapid and specific fluorescent probe based on aggregation-induced emission enhancement for mercury ion detection in living systems

Mercury is a harmful heavy metal that seriously threatens the environment and organisms. In this study, we combined the aggregation-induced emission mechanism and the advantages of peptides to design a novel tetraphenylene (TPE)-based peptide fluorescent probe, TPE-Cys-Pro-Gly-His (TPE-CPGH), in which the sulfhydryl group of Cys in the peptide chain and the imidazolium nitrogen provided by His were used to mimic the Hg2+ binding site of metalloproteins. The β-fold formed by Pro-Gly was used to promote the spatial coordination of the probe with Hg2+ and the formation of the coordination complex aggregates, these changes led to the "turn on" response to Hg2+. The detection of Hg2+ by TPE-CPGH not only showed high specificity and sensitivity (LOD=46.2 nM), but also had the advantages of fast response and applicability for detection over a wide pH range. Additionally, TPE-CPGH effectively detected Hg2+ in environmental samples, living cells and organisms due to its low cytotoxicity, high water solubility and cell membrane permeability. More interestingly, TPE-CPGH was also mitigated Hg2+ exposure-induced oxidative stress toxicity in vitro and in vivo.

Detection and management of coal seam outcrop fire in China: a case study

The outcrop fire area in Rujigou Coal Mine in Ningxia, China has been burning continuously for over 100 years. This not only results in wastage of resources but also poses significant damage to the ecological environment. Previous research on open fire detection has mainly focused on coalfield fire areas, using single method such as infrared remote sensing or surface temperature measurement, magnetic method, electrical method, radon measurement and mercurimetry. However, the outcrop fire area has migrated to deeper parts over the years, conventional single fire zone detection methods are not capable of accurately detecting the extent of the fire zone, inversion interpretation is faced with the problem of many solutions. In fire management, current research focuses on the development of new materials, such as fly ash gel, sodium silicate gel, etc., However, it is often difficult to quickly extinguish outcrop fire areas with a single technique. Considering this status quo, unmanned aerial vehicle (UAV) infrared thermal imaging was employed to initially detect the scope of the outcrop fire area, and then both the spontaneous potential and directional drilling methods were adopted for further scope detection in pursuit of more accurate results. In addition, an applicable fire prevention and extinguishing system was constructed, in which three-phase foam was injected for the purpose of absorbing heat and cooling. Furthermore, the composite colloid was used to plug air leakage channels, and loess was backfilled to avoid re-combustion. The comprehensive detection and control technologies proposed in this study can be applied to eliminating the outcrop fire area and protecting the environment. This study can provide guidance and reference for the treatment of other outcrop fire areas.