In this study, we conducted field experiments aimed at acquiring spectra of Hazardous and Noxious Substances (HNS) and examining their variations. Spectral measurements were conducted at an outdoor pool situated in the CEDRE in Brest, France. Hyperspectral cameras equipped with 160 bands covering the range from 400 to 1,000 nm were employed to capture the spectra. To elucidate the spectral characteristics of HNS, we extracted the radiance values of HNS and conducted a quantitative analysis of the spectral patterns. While different behaviors were observed depending on the specific HNS under investigation, overall, the radiance values of HNS spectra at the peak wavelengths exhibited variations in response to wind conditions. For highly volatile HNS such as toluene and xylene, the radiance difference compared to the surrounding seawater increased under the influence of wind, but subsequently decreased beyond a certain wind speed. Conversely, the radiance difference of the condensate decreased as wind speed increased. This demonstrates the utility of quantitative analysis in enhancing our understanding.
A hazardous noxious substance (HNS) spill accident is one of the most devastating maritime disasters as it is accompanied by toxicity, fire, and explosions in the ocean. In this study, a ground HNS measurement experiment was conducted for artificially spilled HNS by using two hyperspectral cameras at VNIR and SWIR wavelengths. HNS images were obtained by pouring 1 L of toluene into an outdoor marine pool and observing it with a hyperspectral sensor installed at a height of approximately 12 m. The pure endmember spectra of toluene and seawater were extracted using principal component analysis and N-FINDR, and a Gaussian mixture model was applied to the toluene abundance fraction. Consequently, a toluene spill area of approximately 2.4317 m2 was detected according to the 36% criteria suitable for HNS detection. The HNS thickness estimation was based on a three-layer two-beam interference theory model. Considering the detection area and ground resolution, the amount of leaked toluene was estimated to be 0.9336L. This study is expected to contribute to the establishment of maritime HNS spill response strategies in the near future based on the novel hyperspectral HNS experiment.
Monitoring the hazardous and noxious substances (HNS) is a very important issue for mitigating the influence of catastrophic accidents in ocean and coastal areas. However, research on the HNS sensor is just in the beginning stage. In this study, we proposed a new HNS sensor using a printed ITO layer. We carried out a series of experiments of detecting the NH4OH and seawater solution to investigate the feasibility as a HNS sensor. The resistance of ITO layer dropped abruptly when it soaked into the solutions. The resistance change (δR) was linearly correlated with the NH4OH concentration of the solution, also it can be classified into two states; one is the transition stage, the other is the stabilized stage. The former is considered to be caused by the large capacitance of the electrical double layer (EDL) on the ITO surface. Also, the ITO layer showed considerable chemical stability within our experimental condition. In this paper, we have investigated the feasibility of printed ITO layer as a sensitive and cheap HNS sensor.
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