亚洲沙尘中铁、铜对黄海近海表层优势浮游细菌丰度影响的模拟研究

Effects of Iron and Copper in Asian Dust on Dominant Bacterioplankton Abundance in the Surface of the Yellow Sea

本文于2021年夏季在黄海近岸采集表层海水进行室内培养实验。通过添加不同浓度铁、铜以及沙尘来研究沙尘中铁、铜对海洋表层优势浮游细菌丰度的影响。结果表明,在近海富营养区,铁的添加在培养前期可短暂促进优势细菌丰度的增加(为对照组的1.33~6.58倍),其中低浓度铁的促进作用最显著(P<0.05),主要是通过影响优势细菌对溶解无机氮(Dissolved Inorganic Nitrogen,DIN)、溶解态有机物(Dissolved Organic Matter,DOM)和Fe的吸收利用以及对Cu的释放,进而促进细菌生长。铜的添加能在培养后期抑制优势细菌的丰度,其细菌丰度与对照组相比下降2%~53%,高浓度铜对细菌的抑制作用强于低浓度铜,主要通过影响细菌对溶解态有机氮(Dissolved Organic Nitrogen,DON)和Cu的吸收利用以及对NO-2+NO-3、溶解态有机碳(Dissolved Organic Carbon,DOC)和Fe的释放速率,进而影响其生长。沙尘添加对黄海表层近海优势浮游细菌的生长总体上先抑制(比对照组低1%~19%)后促进(比对照组高15%~60%),低浓度沙尘在培养后期对细菌丰度的促进作用显著(P<0.05),沙尘主要通过影响细菌对DIN和DON的吸收释放来影响细菌生长。研究显示,亚洲沙尘沉降对近海富营养区域浮游细菌生长有影响,尤其在培养后期,但这种影响效应不仅仅是铁的促进作用与铜的抑制作用的结果,而是沙尘中营养盐、DOC以及微量金属共同影响的作用。研究结果可为深入探讨沙尘沉降对海洋浮游细菌的影响及其作用机制提供科学参考。

Dust deposition is an important source of nutrients and trace metals in the ocean.At present,there is no systematic study and quantitative evaluation of the effects of dust deposition on the growth of bacterioplankton in eutrophic offshore.To study the impact of iron and copper in the dust on the dominant bacterioplankton abundance in the ocean surface,low and high concentrations of iron and copper as well as dust were added to surface seawaters in three indoor culture experiments in the summer of 2021 with the seawaters collected in the coast of the Yellow Sea.In offshore areas of high nutrients content,our results showed that the abundance of dominant bacteria was temporarily promoted by the addition of iron in the early stage of culture experiment(1.33~6.58 times higher than the control),and the promotion of low concentration iron was the most significant(P<0.05),which could stimulate the bacterial abundance increasing by 6.58 fold.The bacterial growth mainly promoted by changing the absorption of DIN,DOM and Fe as well as the release of Cu by dominant bacteria.The inhibition was observed in the later stage when copper was added to culture experiment,especially with addition of high concentrations of copper,and the bacterial abundance was 2%~53%lower than the control group.It mainly affected the growth of bacteria by promoting the absorption of DON and Cu as well as the release rate of NO-2+NO-3,DOC and Fe.The addition of dust inhibited the growth of dominant planktonic bacteria by 81%~99%than the control at initial stage,and promote the growth of dominant bacterioplankton by 15%~60%higher than the control after an initial 120 h inhibition.The low-concentration dust significantly promoted bacterial growth at the later stage of culture(P<0.05).The dust affected bacterial growth mainly by changing the absorption and release of DIN and DON by bacteria.Studies have shown that dust deposition has an impact on the growth of planktonic bacteria in offshore areas of high nutrient content,especially at the late stage of culture.But this effect was not only caused by the promotion of iron or the inhibition of copper,but the combined effect of nutrients,DOC and trace metals which were released by dust.The results can provide scientific reference for further study on the effect of dust deposition on marine bacteria and its mechanism.