No-interfered and visual evaluation of global warming impacts on phytoplankton-based copper bioavailability and then carbon sequestration.

Global warming has an increasingly serious impact on the ecological environment. Copper bioavailability plays an important physiological role in revealing the mechanism of carbon cycle, photosynthesis, and respiration. Here we reported a multifunctional carbon quantum dots fluorescence probe for no-interfered and visual determination of phytoplankton-based intracellular Cu(II), glucose, and reactive oxygen species (ROS). Glucose and ROS were explored to reflect the change in primary biomass and carbon sequestration. H₂O₂ is acted as the standard material of ROS, and the fitting parameter for glucose and H₂O₂ concentrations was 0.42(r = 0.9972). Both glucose, ROS, and Cu²⁺ detection have advantages of wide linear range (24.8-3.96 × 10⁵ μg/L, 6-9.6 × 10⁵ ng/L and 5-15 × 10³ nmol/L, respectively), high precision (1.22 %, 6.38 %, and 7.37 %, respectively), and low detection limit (86.7 ng/L, 5.32 ng/L, and 0.367 nmol/L, respectively). Cu²⁺ uptake was increased with the increasing of temperature, and the copper bioavailability in increasing order was Cu-PorPhyr > Cu-phthalate > Cu-EDTA. There were significant positive correlation between glucose and Cu²⁺(r = 0.9943). Copper bioavailability would directly affect the carbon sequestration, i.e., when the concentration of intracellular copper increases by 1 mg/L, the content of intracellular glucose increases by 412 mg/L approximately, equally to 2.47 g/L of carbon dioxide was fixed.