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通过室内模拟培养,研究了孔石莼存在下过量无机氮对水体无机碳体系变化的影响及其机制.结果表明,无机氮的添加均会导致水体DIC、HCO3-和p(CO2)的减少,pH和CO23-的增加.当NO3--N和NH4+-N浓度分别低于71μmol·L-1和49.7μmol·L-1时,随着营养盐浓度的增加,水体无机碳体系各组分的变化幅度增大,其中以NO3-3和NH4-3组变化最为明显,至实验结束DIC分别较空白组下降了151μmol·L-1和232μmol·L-1;当NO3--N和NH4+-N浓度分别高于355μmol·L-1和248.5μmol·L-1时,则随着浓度的增加无机碳各组分的变化幅度减小.对无机碳的减少与孔石莼的生长(Δm)做相关性分析发现,二者密切相关(r=-0.91,p<0.0001,n=11),当营养盐浓度促进孔石莼的生长时,水体DIC浓度下降,孔石莼干重增加;反之,当营养盐过量时,则会对其产生毒性作用,抑制其对无机碳的吸收.NH4+-N对海水无机碳体系的影响较NO3--N明显.
The effects of excess inorganic nitrogen on the inorganic carbon system in water and its mechanism were studied by indoor simulated cultivation.The results showed that the addition of inorganic nitrogen would lead to the decrease of DIC, HCO3- and p (CO2) pH and CO23- increased with the increase of nutrient concentration when the concentrations of NO3 - N and NH4 + -N were lower than 71μmol·L-1 and 49.7μmol·L-1 respectively The changes of NO3-3 and NH4-3 groups were the most obvious changes. After the experiment, DIC decreased by 151μmol·L-1 and 232μmol·L-1, respectively. When NO3 - N and NH4 + -N When the concentration was higher than 355μmol·L-1 and 248.5μmol·L-1 respectively, the change range of inorganic carbon decreased with the increase of concentration, and the decrease of inorganic carbon and the growth of pore stone Δ (Δm) Correlation analysis showed that there was a close correlation between them (r = -0.91, p <0.0001, n = 11). When the nutrients concentration promoted the growth of Phyllostachys sylvestris, the DIC concentration in the water decreased and the dry weight of Aphis gossypii increased. On the contrary, When excessive nutrients, it will produce toxic effects, inhibit its absorption of inorganic carbon.NH4 + -N on seawater inorganic carbon system than NO3 - N significantly.