Mapping Dissolved Gases Distribution in Lake Water Using Shipborne Membrane Inlet Mass Spectrometry
As global average carbon dioxide concentrations steadily rise,the frequency,intensity,and duration of cyanobacterial blooms in aquatic ecosystems are increasing annually.This phenomenon presents a significant threat to the overall health of global ecosystems and has garnered worldwide attention.In this study,an online detection of small-molecule dissolved gas concentrations in lake using a home-made membrane inlet mass spectrometer was conducted.Comparative water samples analyses demonstrated that the developed mass spectrometer instrument effectively discriminated between different water samples based on its dissolved gas detection capabilities.Online survey revealed that the concentrations of dissolved O2 and dissolved CO2 were 0.24 mmol/L and 1.31 μmol/L,respectively,in areas without cyanobacterial coverage.In areas with cyanobacterial coverage,their concentrations were 0.21 mmol/L and 0.92 μmol/L,respectively.In areas where cyanobacteria were densely collected,the dissolved CO2 content rose rapidly,while the dissolved O2 content decreased rapidly.This result revealed that large-scale cyanobacterial blooms exacerbated CO2 emissions,and during such blooms,lakes acted as sources of CO2,emitting substantial amounts into the atmosphere,thereby contributing to adverse impacts on global climate change.Furthermore,extensive cyanobacterial blooms led to a rapid decrease in dissolved O2 levels,resulting in O2 depletion and the mortality of fish and benthic invertebrates.The research highlighted the significance of the ratio of content of O2 and CO2 as a crucial indicator for cyanobacterial monitoring,with a smaller ratio indicating higher cyanobacterial content.Moreover,changes in turbidity and variations in the ratio of O2 and CO2 exhibited strong consistency.Large-scale algal blooms increased water turbidity,which posed a threat to the survival of aquatic organisms.This study provided a technological means for online detection of dissolved gases in water,offering essential references for water quality assessment,ecological evaluation,and particularly,for early prevention,mid-term management,and post-treatment effectiveness assessment of cyanobacterial blooms.
Membrane inlet mass spectrometerDissolved gasesOnline detectionAlgae
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