Contrasting responses of DMS and DMSP to ocean acidification in Arctic waters
Contrasting responses of DMS and DMSP to ocean acidification in Arctic waters
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DOI：
10.5194/bg-10-1893-2013
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发表时间：
2013-01-01
期刊：
影响因子：
4.9
通讯作者：
Engel, A.
中科院分区：
文献类型：
--
作者：
Archer, S. D.;Kimmance, S. A.;Engel, A.
在北极等较冷地区，大气中二氧化碳的增加使海洋pH值下降得最快。作为2010年欧洲海洋酸化项目（EPOCA）在Spitzbergen外海的中上层生态系统实验的一部分，我们研究了pH值降低和pCO（2）增加对二甲基硫（DMS）浓度的影响。DMS是北极对流层气溶胶形成和增长的重要反应物和贡献者。在9个初始pH（T）为8.3至7.5，相当于pCO（2）为180至1420 μ atm的中型生态系统中，在添加营养物后，对酸度（氢离子浓度[H+]）的响应非常显著，但相反。与环境[H+]相比，在30天实验的中间阶段，当酸度变化的影响明确时，DMS的平均浓度在最高[H+]时降低了约60%，在[H+]相当于750 mu atm pCO（2）时降低了35%，正如2100年的预测。相比之下，DMS的前体二甲基磺基丙酸酯（DMSP）的浓度在最高[H+]时升高约50%，在[H+]时升高30%，相当于750 μ atm pCO（2）。对浮游植物合成DMSP的比速率的测量表明，在高[H+]时产量增加，与无机碳固定速率平行。在高[H+]下DMSP产量的升高主要是甲藻生物量增加的结果，特别是Heterocapsa rotundata物种丰度的增加。我们讨论了浮游植物和细菌的过程，可以解释的比率降低的DMS：DMSPt（总二甲基磺基丙酸盐）在较高的[H+]。八个处理水平的实验设计提供了相对稳健的经验关系DMS和DMSP浓度，DMSP生产和甲藻生物量与[H+]在北极沃茨。
Increasing atmospheric CO2 is decreasing ocean pH most rapidly in colder regions such as the Arctic. As a component of the EPOCA (European Project on Ocean Acidification) pelagic mesocosm experiment off Spitzbergen in 2010, we examined the consequences of decreased pH and increased pCO(2) on the concentrations of dimethylsulphide (DMS). DMS is an important reactant and contributor to aerosol formation and growth in the Arctic troposphere. In the nine mesocosms with initial pH(T) 8.3 to 7.5, equivalent to pCO(2) of 180 to 1420 mu atm, highly significant but inverse responses to acidity (hydrogen ion concentration [H+]) occurred following nutrient addition. Compared to ambient [H+], average concentrations of DMS during the mid-phase of the 30 d experiment, when the influence of altered acidity was unambiguous, were reduced by approximately 60% at the highest [H+] and by 35% at [H+] equivalent to 750 mu atm pCO(2), as projected for 2100. In contrast, concentrations of dimethylsulphoniopropionate (DMSP), the precursor of DMS, were elevated by approximately 50% at the highest [H+] and by 30% at [H+] corresponding to 750 mu atm pCO(2). Measurements of the specific rate of synthesis of DMSP by phytoplankton indicate increased production at high [H+], in parallel to rates of inorganic carbon fixation. The elevated DMSP production at high [H+] was largely a consequence of increased dinoflagellate biomass and in particular, the increased abundance of the species Heterocapsa rotundata. We discuss both phytoplankton and bacterial processes that may explain the reduced ratios of DMS: DMSPt (total dimethylsulphoniopropionate) at higher [H+]. The experimental design of eight treatment levels provides comparatively robust empirical relationships of DMS and DMSP concentration, DMSP production and dinoflagellate biomass versus [H+] in Arctic waters.