The junction area of Yunnan, Guizhou, and Sichuan provinces is the heaviest coal-burning endemic fluorosis zones in China. To better understand the pathogenicity of endemic fluorosis in this area, 87 coal samples from the late Permian outcrop or semi-outcrop coal seams were collected in eight counties of the junction area of Yunnan, Guizhou, and Sichuan provinces. The total fluorine and sulfate content, etc. in the coal was determined using combustion-hydrolysis/fluoride-ion-selective electrode method and ion chromatography, respectively. The results show that the total fluorine concentrations in the samples ranged from 44 to 382 µg g?1, with an average of 127 µg g?1. The average pH of the coals is 5.03 (1.86–8.62), and the sulfate content varied from 249 to 64,706 µg g?1 (average 7127 µg g?1). In addition, the coals were medium- and high-sulfur coals, with sulfur mass fraction ranging from 0.08 to 13.41%. By heating the outcrop coals, HF release from the coal was verified quantitatively without exception, while simulated combustion directly confirmed the release of sulfuric acid (H2SO4). The acid in coal may be in the form of acidic sulfate (\({\text{HSO}}_{4}^{ - }\)/H2SO4) because of a positive relationship between pH and \(p\left( {{\text{SO}}_{4}^{2 - } } \right)\) in the acidic coal. The possible reaction mechanism would be that a chemical reaction between the acid (H2SO4 or \({\text{HSO}}_{4}^{ - }\)) and fluorine in the coal occurred, thereby producing hydrogen fluoride (HF), which would be the chemical form of fluorine released from coal under relatively mild conditions. The unique chemical and physical property of HF may bring new insight into the pathogenic mechanism of coal-burning endemic fluorosis. The phenomenon of coal-burning fluorosis is not limited to the study area, but is common in southwest China and elsewhere. Further investigation is needed to determine whether other endemic fluorosis areas are affected by this phenomenon. 相似文献
The feasibility of using Phragmites australis-JS45 system in removing nitrobenzene from sediments was conducted. However, it was observed that nitrobenzene degraded rapidly and was removed completely within 20 days in native sediments, raising the possibility that indigenous microorganisms may play important roles in nitrobenzene degradation. Consequently, this study aimed to verify this possibility and investigate the potential nitrobenzene degraders among indigenous microorganisms in sediments. The abundance of inoculated strain JS45 and indigenous bacteria in sediments was quantified using real-time polymerase chain reaction. Furthermore, community structure of the indigenous bacteria was analyzed through high throughput sequencing based on Illumina MiSeq platform. The results showed that indigenous bacteria in native sediments were abundant, approximately 1014 CFU/g dry weight, which is about six orders of magnitude higher than that in fertile soils. In addition, the levels of indigenous Proteobacteria (Acinetobacter, Comamonadaceae_ uncultured, Pseudomonas, and Thauera) and Firmicutes (Clostridium, Sporacetigenium, Fusibacter, Youngiibacter, and Trichococcus) increased significantly during nitrobenzene removal. Their quantities sharply decreased after nitrobenzene was removed completely, except for Pseudomonas and Thauera. Based on the results, it can be concluded that indigenous microorganisms including Proteobacteria and Firmicutes can have great potential for removing nitrobenzene from sediments. Although P. australis - JS45 system was set up in an attempt to eliminate nitrobenzene from sediments, and the system did not meet the expectation. The findings still provide valuable information on enhancing nitrobenzene removal by optimizing the sediment conditions for better growth of indigenous Proteobacteria and Firmicutes.
