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. H ₂ O ₂ is acted as the standard material of ROS, and the fitting parameter for glucose and H ₂ O ₂ concentrations was 0.42(r = 0.9972). Both glucose, ROS, and Cu ²⁺ detection have advantages of wide linear range (24.8-3.96 × 10 ⁵  μg/L, 6-9.6 × 10 ⁵  ng/L and 5-15 × 10 ³  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). Cu ²⁺ 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 Cu ²⁺ (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.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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