溶解无机氮加富对海带养殖水体无机碳体系的影响

Effects of DIN enrichment on inorganic carbon system of Saccharina japonica culture water

中文关键词: 溶解无机氮  无机碳体系  固碳  海带

英文关键词: Dissolved inorganic nitrogen  Inorganic carbon system  Carbon fixation  Saccharina japonica

中文摘要:

      通过室内模拟实验，研究了在海带养殖水体中添加不同浓度的无机氮（NO₃^--N和NH₄⁺-N）对海水无机碳体系的影响。结果表明，无机碳体系各组分的变化趋势与无机氮添加浓度和无机氮形态有关。当NO₃^--N和NH₄ -N浓度范围分别在4.73-52.78 µmol/L和2.56-34.66 µmol/L时，DIC、HCO₃^-和pCO₂均随着营养盐浓度的增加呈下降趋势，其中以NO₃^--3和NH₄ -3组变化最为明显，均达到最低值，分别为2054和2112 µmol/L、1776和1869 µmol/L、86和114 µatm；而当NO₃^--N和NH₄ -N浓度范围分别为52.78-427.29 µmol/L和34.66-268.33 µmol/L时，DIC、HCO₃^-和pCO₂随着营养盐浓度的增加，其下降幅度逐渐减弱，但实验结束时DIC、HCO₃^-和pCO₂仍低于对照组。NO₃^--N对海带养殖水体无机碳体系的影响较NH₄ -N明显，加NO₃^--N组对水体的固碳能力显著高于加NH₄ -N组。因此，当NO₃^--N和NH₄ -N浓度分别为52.78 µmol/L和34.66 µmol/L时，海带的光合固碳能力达到最大，过高或者过低均会降低海带对水体无机碳的吸收固定。

英文摘要:

      Effects of dissolved inorganic nitrogen (NO₃-^{-N and NH₄+-N) addition on dissolved inorganic carbon (DIC) system of Saccharina japonica culture water were studied. The results indicated that the inorganic carbon system was correlated with the concentrations and forms of DIN. The concentrations of DIC, HCO₃- and pCO2 decreased with the increasing nitrogen concentration in the range of 4.73-52.78 µmol/L (NO₃--N) and 2.5-34.66 µmol/L (NH4 -N), and they were most remarkably affected by the NO₃--3 and NH4 -3 treatments, corresponding with the lowest values of 2054 and 2112 µmol/L, 1776 and 1869 µmol/L, 86 and 114 µatm, respectively. However, when the concentration of nitrogen was between 52.78-427.29 µmol/L (NO₃--N) and 34.66-268.33 µmol/L (NH4 -N), the falling trends of DIC, HCO₃- and pCO2 were weakened with the increasing nitrogen, but the concentrations of DIC, HCO₃- and pCO2 were also lower than the control. Influence of NO3--N addition on the inorganic carbon system of seawater was larger than NH4 -N addition, and the ability of carbon fixation in NO₃--N treatment was significantly higher than in NH4 -N treatment. The highest capacity of photosynthetic carbon fixation by S. japonica appeared in 52.78 µmol/L (NO₃--N) and 34.66 µmol/L (NH4 -N). The DIC assimilation ability by S. japonica would decrease when NO₃--N and NH4 -N deviated from the optimum values.}