基于分光光度法的pH测量在海洋碳酸盐系统观测中的研究进展OA

[Background]Spectrophotometric pH measurement method has emerged as a key method in marine carbonate chemistry due to its high measurement precision,excellent comparability,and strong potential for standardization.As concerns about ocean acidification,the global carbon cycle,and climate change intensify,accurate,consistent,and scalable pH observation techniques are increasingly critical.Traditional glass electrode methods often suffer from drift and limited reproducibility in long-term or in situ applications,while spectrophotometric approaches offer traceability to primary standards.In recent years,this method has been widely adopted in global ocean observation networks,carbon monitoring programs,and biogeochemical research,providing high-quality pH data across various temporal and spatial scales.Moreover,it has shown potential for extending into multi-parameter observations and autonomous systems,making it a cornerstone technique in both research and operational oceanography.[Progress]In recent years,the spectrophotometric pH measurement method has made significant advances in the observation of marine carbonate systems.Measurement methods and instruments have developed along a dual-track trajectory.Manual systems have become increasingly miniaturized,portable,and intelligent,enabling rapid in situ measurements and facilitating citizen science participation,whereas automated systems have been continuously refined in terms of precision,stability,robustness,and environmental adaptability,supporting reliable deployment in deep-sea,open-ocean,and long-term fixed-point monitoring.Research on pH indicators has achieved substantial progress in purification techniques,absorbance parameter correction,and standardization,markedly improving measurement precision,reproducibility,and accuracy,and providing a solid foundation for establishing standardized protocols and consistent observational frameworks.The application of the spectrophotometric pH measurement method in the carbonate system has expanded to include key parameters such as total alkalinity(TA),dissolved inorganic carbon(DIC),and carbonate ion concentration[c(CO32-)].With the continuous refinement of methods and instrumentation,analytical performance has been significantly improved,and a transition from single-parameter to dual-parameter measurements is gradually being achieved.Moreover,studies on carbonate system consistency,including measurement protocols,reagent standards,sample preservation,and model applicability,have laid a strong groundwork for method standardization and ensured reliable application across diverse water bodies and geographic regions.Collectively,these advances demonstrate the maturity and expanding capability of spectrophotometric pH measurement method in supporting high-precision,standardized observations of marine carbonate chemistry.Amid growing global attention to ocean acidification,carbon cycle research,ocean alkalinity enhancement(OAE),and the demand for"climate"goals observation accuracy,the development of the spectrophotometric pH measurement method is evolving toward higher levels of technological integration,parameter expansion,and system-wide standardization.These trends reflect the method's increasing role as a foundational tool in both scientific research and operational oceanography.[Perspective]Looking ahead,several directions are emerging as critical for enhancing the accuracy,reliability,and applicability of the spectrophotometric pH measurement method in global ocean observation.One major challenge is the lack of a unified indicator dye production and traceability system.Establishing a standardized supply chain,along with certified reference materials and traceability protocols,will be essential for minimizing inter-laboratory discrepancies and ensuring data comparability.Expanding applicability to more complex and variable environments,such as high-latitude,estuarine,or eutrophic waters,remains an important objective.This requires improving temperature and salinity compensation models and validating them under diverse field conditions.Furthermore,the integration of the spectrophotometric pH measurement method with other carbonate system parameters,particularly through multi-parameter joint measurements and consistency-based inversion methods,will be critical for enabling comprehensive system diagnostics.Emerging carbonate system variables,such as c(CO32-),are gaining attention for their biogeochemical relevance and potential role in refining assessments of ocean acidification and alkalinity enhancement impacts.Incorporating these parameters into spectrophotometric platforms will strengthen their analytical scope.From an engineering perspective,future efforts should focus on miniaturization,antifouling measures,and autonomous system integration,especially for long-term in situ deployments.Advances in optical design and fluidic control will also contribute to more efficient and scalable instrument architectures.Ultimately,the transition of the spectrophotometric pH measurement method from a laboratory-based technique to a robust,systematized observational platform will play a pivotal role in supporting high-resolution ocean carbon monitoring and international climate assessment initiatives.Its development aligns closely with the growing need for accurate,scalable,and climate-grade biogeochemical observations.