Dual-modal detection of seawater dissolved organic matter using fluorescence imaging processing and absorbance spectroscopy

Dissolved organic matter (DOM) is an important component of organic substances in seawater, and its concentration detection is of significant importance for marine environmental monitoring and carbon cycle studies. This study addresses the need for rapid detection of seawater DOM and innovatively proposes a dual-modal detection method combining laser-induced fluorescence imaging with UV-visible absorptiometry. The study employs 266nm ultraviolet laser to excite fluorescence signals from DOM, captures the fluorescence using a CMOS image sensor, and extracts color features with image processing techniques. A partial least squares regression model was constructed to achieve high-sensitivity detection in lower concentration ranges (error < 12%). Simultaneously, the UV absorption method was used to establish a linear response at the 266nm characteristic wavelength (error < 15%), constructing a complete concentration detection system. Based on this method, a detection system was developed in this study, using sodium humate to simulate seawater DOM. Through standardized sample preparation and dual-modal system integration, continuous detection across a wide concentration range was achieved, with an error of less than 18% in real water sample tests. The system offers high accuracy, low cost, and rapid response, providing a novel technological solution for real-time marine environmental monitoring.