Accurate method of generating infrared imaging features by the angular disturbance of an airborne platform.

The imaging quality of an airborne infrared (IR) system is limited by the angular disturbance of the airborne platform. Based on the full-chain (IR scene-atmosphere-optical system-detector-airborne platform) signal transmission process, this study focused on the low-frequency sinusoidal angular disturbance features of the airborne platform and accurately calculated the point spread function caused by the angular disturbance and the IR imaging features when the IR system's different locations were dynamically simulated in a three-dimensional scene. First, the degradation mechanism of the IR imaging features resulting from the angular disturbance was analyzed from the viewpoint of scene radiation signal transmission and detector sampling. Then, the dynamic simulation in the three-dimensional scene resulting from the angular disturbance was realized by considering the geometric transformation of the spatial imaging, scale registration of the spatial sampling, radiation coupling, and angular disturbance caused by the airborne platform. Finally, the distances detected under different disturbance conditions were predicted using the established model. The obtained results provide data supporting the demonstration, verification, and optimization of the IR imaging system's design scheme.

[Occurrence and Distribution of Potential Dangerous Biological Agents in Beijing Suburban Rivers].

Dangerous biological agents （DBAs） refer to microorganisms, toxins, and other biological substances that have the potential to cause significant harm to humans, animals, plants, and the environment. They are the primary target of the prevention and response in China's Biosafety Law, and it is of great importance to clarify the characteristics of DBAs in the Beijing suburban rivers for the insurance of the water safety in Beijing. The typical Beijing suburban rivers （Mangniu River, Chaohe River, and Baihe River） were selected, and the occurrence and distribution of DBAs concerning the molecular biology composition as the nucleic acid （antibiotic resistance genes, ARGs）, nucleic acid and proteins （viruses）, and intact cellular structures （pathogens） were determined based on the metagenomics. The results showed that there was a high abundance of multidrug-resistant ARGs in the water and substrates of the urban river； on average, they made up 74.11% ±6.82% of the total, and the abundance of aminoglycoside and MLS （macrolide-lincosamide-streptomycin）-resistant ARGs was the highest, but the predominant subtypes of ARGs were of low risk and had limited transmission potential. The viruses in the tributary mainly belonged to the phages, most of which were Kyanoviridae and Peduoviridae, with averages of 16.98% ±8.44% and 16.19% ±10.79%, respectively. Eukaryotic viral populations consisted mainly of members from the Mimiviridae and Phycodnaviridae families, with averages of 10.37% ±12.68% and 8.34% ±6.97%, respectively, whereas there were few viruses related to human and animal diseases. The pathogenic bacteria mainly contained Neisseria meningitidis, Brucella suis, Salmonella enterica, and Burkholderia pseudomalle, with averages of 19.17% ±3.63%, 12.76% ±2.88%, 11.22% ±1.95%, and 8.26% ±1.84%, respectively. The composition and abundance of pathogenic bacteria varied significantly among different tributaries and locations, possibly owing to water quality, pollution sources, environmental factors, and human activities. These findings can provide data support for the water safety management and biological risk control of Beijing suburban rivers.

[Effects of Nitrogen Speciation Transformation on Microbial Community Succession in Input Rivers of Miyun Reservoir].

The Miyun Reservoir is the major source of surface drinking water in Beijing. However, the total nitrogen (TN) concentrations in the Miyun Reservoir and inflowing rivers have recently been increasing. In this study, the Mangniu River, a typical inflow river in the upper reaches of the Miyun Reservoir, was selected as the study area to investigate the spatial distribution and transformation of various nitrogen forms from the perspective of microbial community composition and predicting function, aimimg at providing a scientific reference for nitrogen pollution control of the Miyun Reservoir. The results indicated that except for TN, all the other physical and chemical water quality indicators in the upper reaches of the Miyun Reservoir met the Class II criteria of the environmental quality standards for surface water in China (GB 3838-2002). Additionally, NO3--N was the primary constituent of TN, ranging from 77.7% to 92.9%. Banchengzi Reservoir has a certain self-purification ability because its high C/N ratio promotes denitrification. Significant differences in microbial community structure were observed between the water and sediments of Mangniu River along with spatial distribution. High NO3--N concentration was the major environmental factor affecting the succession of microbial community structure. Many nitrification and denitrification microorganisms existed in Mengniu River, and the relative abundance of denitrification bacteria (DNB) was higher than that of nitrification bacteria, and that in the sediments was slightly higher than that in the water. Nitrosopumilus and Pseudomonas were the dominant nitrification and denitrification bacteria in Mengniuhe River, respectively. The results of phylogenetic investigation of communities by the reconstruction of unobserved states (PICRUSt2) showed that NO3--N reduction module was the major nitrogen metabolism module, which primarily occurred in water. The abundance of the functional genes for nitrification (i.e., narGH) was the highest in water, and the major functional gene involved in NO3--N reduction was nirBD of DNRA, which was primarily present in the sediments; however, the main functional gene involved in denitrification was nirK.

[Impacts of Riparian Buffer Zone Type on Reduction in Runoff Pollution in the North Canal River Under Different Rainfall Events].

The impact of non-point source pollution on the water quality of the North Canal River is becoming increasingly prominent. In this study, the riparian buffer zones (RBZ) of the Nansha River and Beisha River, the inlet tributaries of the Shahe Reservoir in the North Canal basin, were selected to investigate the purification effect of riparian buffer zones on runoff pollution during the rainfall process. Two RBZ types, Type I RBZ (levee-flood control retaining wall-woodland-grassland) and Type Ⅱ RBZ (levee-woodland-grassland), were classified by the distribution characteristics of RBZ structure and plant communities in the North Canal River basin. The north bank of the Nansha River (NB) and the south bank of the Beisha River (BN) are typical of Type I RBZ, with low total vegetation cover, "short and steep" slopes, and low herbaceous cover but high diversity. The south bank of the Nansha River (NN) is a typical representative of Type Ⅱ RBZ, with "long and slow" slopes and high herbaceous cover (29.16%) but low diversity. In order to investigate the impacts of rainfall characteristics and RBZ types on the runoff pollutant, a 1 km area in each of the three RBZs was selected to carry out the RBZ non-point source pollution prevention and control engineering trials. The results indicated that Type I RBZ required less time and rainfall to produce runoff and had a greater peak runoff. Type Ⅱ RBZ produced runoff only under heavy rainstorm conditions, with greater runoff retention capacity. Energy dissipation ponds with gravel as the main fillers were set up at the runoff inlets of the RBZ, which effectively reduced runoff pollution. ρ(NH4+-N) and ρ(NO3--N) in the runoff were below 1.6 mg·L-1; ρ(TN) was below 5 mg·L-1; and ρ(PO43-P), ρ(DTP), and ρ(TP) were below 1.0 mg·L-1. The grass ditch of the RBZs effectively reduced ρ(NH4+-N) of the runoff. The retention rate of SS and the reduction effect of pollutants in Type Ⅱ RBZ were better than those in Type I except under heavy rainstorm conditions, which is related to the different RBZ structures and vegetation cover. The correlation analysis results showed that slope length, slope gradient, vegetation cover, and rainfall characteristics were significantly correlated with runoff SS, COD, nitrogen, and phosphorus pollution.

[Effect of Aeration Strategies on Emissions of Nitrogenous Gases and Methane During Sludge Bio-Drying].

The data on nitrogen gas (NH3, N2O, NO) emissions during sludge bio-drying process in China is scarce, especially NO due to its unstable chemical property. In this study, effect of two aeration modes on emissions of methane and nitrogenous gas was compared during the continuous aerated turning pile sludge bio-drying process at full scale. In these two aeration strategies, the one currently used in the plant was set as the control, and the other was set as the test in which the aeration was used for oxygen supply, pile temperature control, and moisture removal in the start-up, middle and final stages, respectively. The results showed that the aeration strategy used in the test could not only obviously accelerate the rate of sludge drying (the moisture contents of the test and the control were 36.6% and 42% on day 11) , but also had a better drying performance (the final moisture contents of the test and the control were 33.6% and 37.6%, respectively) and decreased the ammonia cumulative emission by 5%, (ammonia cumulative emission of the test and the control were 208 mg x m(-3) and 219.8 mg x m(-3), respectively). Though a lower accumulated emission (eCO2) of greenhouse gas in the test at 3.61 kg x t(-1) was observed than that of the control (3.73 kg x t(-1) dry weight) , the cumulative emission of NO in the test at 1.9 g x m(-2) was 15. 9% higher than that of the control (1.6 g x m(-2)).