Immunoanalysis Methods for the Detection of Dioxins and Related Chemicals

sensor

Characteristics, controlling factors and exploration prospects of microbial dolomite reservoirs in the second member of Dengying Formation, Penglai-Zhongjiang area of central Sichuan Basin

The formation and evolution of dolomite reservoirs in the Sinian Dengying Formation in the Sichuan Basin have attracted much attention recently. Due to their economic significance for hosting natural gas resources, determining the key factors that govern the formation and evolution of these dolomite reservoirs are important for hydrocarbon exploration and development. Based on the drilling and seismic data in the Penglai-Zhongjiang area of the Sichuan Basin, the main controlling factors for the development of high-quality reservoirs in the second member of Dengying Formation are investigated by integrating core and thin section observation and geochemical analysis. Lithologies of the reservoirs in the second member of Dengying Formation are dominantly microbial dolomites, dolo-grainstones, and brecciaed dolomites. Moreover, reservoir spaces in these dolomites are mostly dissolution pores, residual framework pores, and breccia pores. The porosity ranges from 2.0% to 8.0% with an average of 4.39%, and the average permeability is 0.53×10-3 μm2, and the reservoir thickness is 170-320 m. Synsedimentary faulting had caused the differentiation of depositional paleo-geomorphology and led to the formation of submarine high barriers, which provided favorable conditions for the development of microbial mound (reef) and shoal complexes. Furthermore, fault activities could have broken the weakly consolidated carbonate sediments into breccias, thus resulting in the brecciaed dolomite reservoir. Penecontemporaneous dissolution is the key to the development of high-quality reservoirs in the second member of the Dengying Formation, which is consistent with their occurrence in the upper part of the shallowing-upward cycles. Differentiation in microfacies leads to distinct diagenetic pathways and porosity evolution of these microbial-dominant carbonate sediments. Overall, dolomite cementation during shallow burial had controlled thedegree of pore preservation. It is predicted that three fault-controlled, platform-margin mound regions in the study area, i.e., Penglai-Zhongjiang, Yanting-Mianyang, and Cangxi-Guangyuan, with areas of 1 600 km2, 1 870 km2 and 2 280 km2, respectively, had been developed in the second member of Dengying Formation in the north slope of the central Sichuan paleo-uplift, showing multi-stage and multi-zone characteristics. Microbial mounds in the platform margin of the second member of Dengying Formation in the Yanting-Mianyang and Cangxi-Guangyuan areas, with three sets of high-quality source rocks, may form a variety of favorable source-reservoir combinations. Additionally, the accumulation conditions may have been superior. The estimated natural gas resources in the study area, over one trillion square meters, makes it a favorable area for ultra-deep carbonate exploration and is expected to be a breakthrough site for the next one trillion square gas field in the Sichuan Basin

Development and Application of a Novel Bioassay System for Dioxin Determination and Aryl Hydrocarbon Receptor Activation Evaluation in Ambient-Air Samples

Airborne persistent toxic substances are associated with health impacts resulting from air pollution, for example, dioxins, dioxin-like polychlorinated biphenyls, and certain polycyclic aromatic hydrocarbons (PAHs), which activate aryl hydrocarbon receptors (AhR) and thereby produce adverse outcomes. Thus, a bioassay for evaluating AhR activation is required for risk assessment of ambient-air samples, and for this purpose, we developed a new and sensitive recombinant mouse hepatoma cell line, CBG2.8D, in which a novel luciferase-reporter plasmid containing two copies of a newly designed dioxin-responsive domain and a minimal promoter derived from a native gene were integrated. The minimal detection limit for 2,3,7,8-tetrachlorodibenzo-<i>p</i>-dioxin with this assay system was 0.1 pM. We used CBG2.8D to determine dioxin levels in 45 ambient-air samples collected in Beijing. The measured bioanalytical equivalent (BEQ) values were closely correlated with the toxic equivalent values obtained from chemical analysis. In haze ambient-air samples, the total activation of aryl hydrocarbon receptors (TAA) was considerably higher than the BEQ of dioxin-rich fractions, according to the results of the cell-based bioassay. Notably, the haze samples contained abundant amounts of PAHs, whose relative toxicity equivalent was correlated with the TAA; this finding suggests that PAHs critically contribute to the AhR-related biological impacts of haze ambient-air samples