【作者】 刘莹；

【导师】 高会旺；

【作者基本信息】 中国海洋大学 ， 环境工程， 2014， 博士

【摘要】 大气沉降能够为海洋提供生物可利用营养盐如氮（N）、磷（P）、硅（Si），以及痕量金属如铁（Fe）、锰（Mn）等，因此成为影响海洋浮游植物生长和初级生产的重要因素。大气沉降不仅可以促进浮游植物生物量的增加，也可以改变浮游植物的种群结构，甚至触发水华的发生，从而调节海洋的固碳能力，最终对海洋生物生产和气候产生影响。沙尘沉降作为大气沉降的重要方面，具有影响范围广，短时间内沉降量大等特点，得到了学界的特别关注。源于世界四大沙尘排放区之一的亚洲沙尘可通过长距离传输，对中国近海甚至北太平洋产生影响。本研究基于2011年3月、2011年5月、2013年3月及2013年6月在中国近海，包括南黄海、东海东部、南海东北部进行的亚洲沙尘及不同营养盐加富的船基围隔培养实验，探讨了大气沉降对中国近海生态系统的影响。2011年3月份，南黄海的培养实验表明：（1）海水表层温度（SST）是影响黄海3月份浮游植物生长最主要的物理因子，而光合有效辐射（PAR）在实验期间影响不大。（2）较高浓度沙尘（Dust-b）与对照组相比，可明显促进浮游植物生物量的增加，且该促进作用主要归因于N的施肥作用和可溶性Fe及其他痕量元素的协同作用。而低浓度沙尘添加提供的营养盐不足以引起浮游植物的明显响应。（3）N对浮游植物的促进作用最为明显，表明N为南黄海中部3月份首要的限制性营养盐。（4）雨水的添加可以明显促进浮游植物的生长，表明雨水的促进作用，然而其N转化为叶绿素的效率（CEI）低于对照组，因此雨水的促进与抑制作用并存。（5）在整个培养实验过程中，浮游植物的粒级分布没有发生明显变化，主要由微型浮游植物（nano级）组成。2013年6月份，南黄海的培养实验表明：（1）从3月份到6月份，黄海藻类生长的限制因子发生了变化，P成为南黄海夏季藻类的首要限制因子，而N的添加不能明显促进藻类的生长。（2）浮游植物的生长对沙尘和雨水的添加均没有足够的响应，仅在实验的前4天有微弱的促进作用，可能沙尘提供的营养盐主要为DIN，而P浓度很低，所以促进作用不明显。（3）夏季黄海以微微型（pico级）浮游植物为主体，在黄海中部G6站位的实验中pico级浮游植物始终为生物量主要贡献者，而在H7站位群落结构发生了变化，nano级浮游植物在实验后期成为优势种。（4）夏季南黄海中部主要由具刺原甲藻（Prorocentrum dentatum）和微型甲藻（Dinoflagellate）为优势藻。G6站位，沙尘的添加主要促进了菱形藻（Nitzschia.sp）的生长。加N+P、N+P+Fe组，微型甲藻和微小原甲藻（Prorocentrum minimum）为优势藻种。H7站位，加P、N+P、N+P+Fe组，浮游植物优势种各不相同。加P组，微小原甲藻和菱形藻的生长是生物量的主要贡献者。加N+P及N+P+Fe组，由于N、P的共同添加促进了硅藻的生长，只是优势种各不相同。2011年5月份，东海的培养实验表明：（1）较高浓度的沙尘有微弱的促进作用，而低浓度沙尘由于释放营养盐浓度太低而没有促进作用；（2）N的添加可以明显促进浮游植物生长，而P、Fe组没有明显变化，表明5月份该海域不受P、Fe限制；（3）培养实验中，浮游植物的粒径结构发生了变化，初始小型浮游植物（micro级）略占优势（38.5%），实验结束时，微型浮游植物（nano）逐渐演变成为优势种，而且对P+Fe与N添加的响应更敏感。2013年春季，南海的培养实验表明：（1）在南海东北部的A3和A6站位，沙尘气溶胶的添加以及N、N+P、N+P+Fe都在很大程度上促进了浮游植物的生长，而雨水和P的添加没有明显的促进作用。而在营养盐浓度更低的WG2站位，对所有处理组都有正面响应；（2）在A3站位所有添加实验中，角毛藻属（Chaetoceros spp）和丹麦细柱藻（Leptocylindrus danicus）为优势种，但在实验结束时均发生角色互换。在A6站位沙尘和营养盐的添加实验中，硅藻中的角毛藻属始终为优势藻。WG2站位甲藻中的双鞭毛藻（Dinoflagellate）为优势种。沙尘及营养盐的添加主要促进了菱形硅藻属（Nitzschia.sp）的增长，而N的添加则主要刺激了角毛藻属的生长。通过多次沙尘及营养盐加富的围隔培养实验，表明在不同营养水平的海域，浮游植物响应各异：（1）南黄海中部，大气沉降的施肥效应在春季较明显，并且春季与夏季浮游植物生长由N限制转换为P限制。夏季营养盐的添加则主要促进了硅藻门的生长；（2）东海东部春季浮游植物生长受N限制影响，由于沙尘提供的N营养盐量不足，因此浮游植物对沙尘添加响应不明显；（3）大气沉降对南海东北部具有明显的促进作用，并且主要促进了硅藻门的生长。更多还原

【Abstract】 Atmospheric deposition has been considered an important source of bio-availablenutrients such as N, P, Si and trace metals like Fe and Cu to phytoplankton living inshelf seas and open oceans. It has been proposed that this external nutrient/trace metalinput enhances primary production (PP) and changes the structure and metabolism ofmicrobial planktonic communities, and may even trigger biogenic blooms in oceans.So could regulate atmospheric CO2through their mediation in the sea-air CO2exchange process, and influence the marine production and chimate. As an importantaspect of atmospheric deposition, the character of dust deposition were the largerinfluence area and the higher deposition amounts in short time, so has received morespecial attention in recent years. Asian dust is one of the four major dust emissionzones in the world, and can impact the China marginal seas, even North Pacific Oceanthrouth long-distance transport. On-board incubation experiments were performed inMarch and May of2011, March and June of2013to explore the responses ofchlorophyll a concentration to Asian dust and various combinations of addedsubstances in China marginal seas, including Southern Yellow sea (SYS), East ChinaSea (ECS) and Southern China Sea (SCS), to explort the influence of Asian dustdeposition on the ecosystem of China marginal seas.The incubation experiments conducted in March of2011suggested:1) Thesurface seawater temperature (SST) maybe the most important physical factor forbiogenic bloom at our study ocean area, and photosynthetically available radiation(PAR) had little change;2) The relatively large amount of Asian dust (Dust-b) addedcould promote a greater increase in phytoplankton biomass, in contrast to the control,and the promotion effect was partially associated with the added N and also partiallyrelated to the increase of the CEI and the synergistic effect of macronutrients and tracemetals leached from the Asian dust. However, treatment with a lower amount of Asiandust (Dust-a) had no significant influence on either concentrations of Chl a or the CEI in contrast to the control;3) The addition of N exhibited a promotion effect on Chl aconcentration indicated the N limitation in the SYS;4) The addition of rainwater hada promotion effect on the growth of phytoplankton, however, calculated CEI waslower than that in the control, suggesting that the inhibition effect coexisted with thepromotion effect;5) The size structure of phytoplankton had shifted to some extent,while nano-phytoplankton was always the predominant species.Incubation experiments conducted in June of2013in SYS suggested:1) FromMarch to June, P has become the first limiting factor at the same region, but theaddition of N could’t promote the growth of phytoplankton;2) For the lower Chl aand nutrients concentration in central of SYS, there was no obvios response to theaddition of Asian dust aerosol and rainwater, maybe for the most of nutrients suppliedthrough dust was DIN, and the amount of P was lower;3) At G6station,picophytoplankton was always the predominant throuthout the experiment, but at H7,the size structure of phytoplankton shifted, nanophytoplankton became predominantspecies at the end of experiment;4) Prorocentrum dentatum and Dinoflagellate werethe dominant species in summer of SYS. At station of G6, for the addition of dustpromote the growth of Nitzschia.sp. In the N+P, N+P+Fe groups, Dinoflagellate andProrocentrum were the dominant species. For station of H7, the dominant specieswere Prorocentrum minimum and Nitzschia.sp in P treatmens, addition of N and Ppromote the growth of Diatom, but the dominant species were different.Experiments conducted in May of2011in ECS suggested:1) The higherconcentration of dust had promotion effect, but the lower amount had no effect on thephytoplankton biomass;2) Additon of N had the obvious promotion effect, however, P,Fe and P+Fe had no obvious fertilization effect, so they were not the limiting factorsin May;3) Microphytoplankton was the predominant in the original seawater (38.5%),but nanophytoplankton became predominant species from9thday to the end, andespecially in the P+Fe and N treatmens.Experiments conducted in SCS at spring of2013suggested:1) At station of A3and A6, the addition of Asian dust aerosol and N, N+P, N+P+Fe could increase thebiomass obviously. At WG2station, maybe for the oligotrophic nutrients condition, all treatments including P and rainwater had positive effect;2) At station of A3,Chaetoceros spp and Leptocylindrus danicus were the predominant species in all thetreatmens. But Dinoflagellate was the predominant at station of WG2, and thenbecame Nitzschia.sp for the addition of Asian dust aerosol and nutrients, andChaetoceros spp in the N-added group.From the four mesocosm experiments conducted in China marginal seas showedthat in marine environment with different nutrients conditions, the response ofphytoplankton to the addition of Asiand dust were various.1) In central of SYS, thefertilization effect of atmospheric deposition was obvios in spring, and the limitingfactor was N in March, changed to P in June, and the ddition of nutrients mainlypromoted the gowth of Diatom;2) For the eastern of ECS, N was the first limitingfactor in sping, and for the lower amount of DIN released from the Asin dust, so theinput had little impact on the algae growth;3) Atmospheric deposition had obviouspromotion effect in the northeast of SCS, and mainly promoted the growth of Diatom.更多还原