【作者】 丁月旻；

【导师】 周名江； 颜天；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋生态学， 2014， 博士

【摘要】 本论文研究了黄海绿潮发生过程中不同海域浒苔体内的元素成分、营养成分和色素含量的变化及与环境营养盐变化的关系；在自然海水中模拟研究了不同生物量下浒苔对海水中碳、氮、磷、硫的消耗作用，转化作用以及释放作用，探讨了浒苔绿潮通过这些作用可能对黄海生态系统造成的影响。主要结果如下：通过测定了现场调查不同海域浒苔的组成成分以及在室内实验研究了在不同营养盐水平下浒苔的色素变化。结果发现，在江苏沿岸海域所采集的浒苔中的主要元素成分（C、N、P等）、营养成分（粗蛋白和粗脂肪）以及6种色素(叶绿素a、叶绿素b、叶黄素、β-胡萝卜素、新黄质和紫黄素）含量明显高于山东半岛海域。通过相关性分析得到，与叶绿素呈显著正相关关系的成分有C、N、Fe、Al、K和粗蛋白。无机氮营养盐浓度水平越高，浒苔的色素含量越高并且绿色越深；而无机磷营养盐单独对浒苔的色素和颜色没有明显影响。无机磷和无机氮对浒苔的色素和颜色的影响有协同作用。因此，在绿潮由江苏沿岸海域向山东半岛海域漂移的过程中，浒苔的绿色由深变浅，叶绿素的含量逐渐减少，多种元素成分含量逐渐减少，营养状态逐渐变差。黄海海域浒苔状态的转变与水体环境因子营养盐的分布有密切联系。通过研究不同生长阶段的浒苔对生源要素的消耗，发现当成体浒苔生物量为2.5g/L时，海水中DIN的消耗率高达约70%，DIP消耗率约为25%，DIC的消耗率率约为42%，而对海水中硫酸盐的消耗率仅约为1%。漂浮的成体浒苔生长率显著高于固着的成体浒苔，而固着和漂浮的浒苔对无机氮、磷营养盐的吸收没有显著差异（P<0.05）。固着期的浒苔对NH4+和PO43-的消耗要高于萌发期的浒苔。浒苔绿潮对海水氮磷营养盐的消耗会明显降低其在海水中的浓度和含量，但绿潮对无机碳和无机硫的消耗对其海水环境的变化没有明显的影响。为了更好地模拟海洋现场情况，在流水体系中研究了浒苔对氮磷营养盐吸收，与非流动水体系进行对比，并研究了浒苔对生源要素的转化作用，得到结果：在海水不流动的实验体系中，2d内浒苔对海水中DIN、 DIP和DOP是有吸收作用的，但对DON有释放作用的。浒苔可将海水中无机氮营养盐转化为有机氮产物。在海水流动的实验体系浒苔对海水中DIN、DIP、DON和DOP都有吸收作用，平均吸收速率分别为10.87μmol·g-1·d-1、2.41μmol·g-1·d-1、0.183μmol·g-1·d-1和0.023μmol·g-1·d-1。浒苔对无机形态的氮、磷、碳和硫转化为自身有机形态的效率分别为：97.33%、99.99%、96.84%和95.31%。爆发的绿潮能将无机形态的生源要素转化为自身有机形态，并将其输送至山东半岛海域。在浒苔腐烂分解的模拟实验中，发现浒苔的分解主要以有机态营养盐释放。2.5g/L的浒苔分解水体中总有机碳、总有机氮和总有机磷的增长到最高浓度分别为1.65mmol/L、80.71μmol/L和1.605μmol/L，均远高于海水原始浓度3-9倍，所占。总氮浓度超过了水体富营养化的标准。氨氮的浓度在分解后期高于海水原始浓度，达到2.46μmol/L。总有机硫、无机硫和硫化氢在分解过程中均有小幅度的升高，不足以影响海水环境。2.5g/L的分解的浒苔水体中溶解氧在12d后低于4mg/L，海水呈现低氧状态；pH值在12d以后一直低于7.5。溶氧和pH水平仅符合第四类海水质量标准。绿潮的腐烂分解会造成水体的缺氧和加重水体营养盐水平，对环境有明显的影响效应。我们的研究发现，黄海大规模浒苔绿潮的爆发对该海域生源要素的迁移、转化有重要影响，浒苔绿潮盛期的巨大生物量能从海水中吸收固定36万吨的碳、2.3万吨的氮、400吨的磷和1.6万吨的硫，并随绿潮的迁移而发生迁移，将大量的营养物质从江苏沿岸海域输送至山东半岛海域。在富营养化水平较高的江苏沿岸黄海海域，绿潮对营养盐的消耗量占全年江苏省排放氨氮量不到15%，这种消耗不能明显降低该海域的营养盐水平；在营养盐相对较低的山东半岛南部海域，绿潮对氮和磷营养盐的消耗较高（79%/d和36%/d），会显著降低该海域的营养盐水平，以致可能不利于其他初级生产者如浮游植物的生长，但会降低发生赤潮的机会。绿潮在山东半岛近岸海域下沉后的消亡分解在大约80天完成，并将自身的营养物质几乎全部释放到海水中，改变水体原有的氮磷营养盐比例（有机营养盐的百分比例从25%左右升高至90%以上），并且可能引起山东半岛沿岸海域局部水体营养盐水平升高（总氮浓度高于80μmol/L）以及水体处于低氧状态（DO低于4mg/L）。黄海大规模浒苔绿潮对海水中营养盐的吸收、迁移和再释放有可能对该海域营养盐的再分布起到重要作用，并产生相应的生态效应。更多还原

【Abstract】 Field surveys were conducted to study the chemical composition and pigmentsin U. prolifera from different coastal area in the Yellow Sea, analyse the relationshipbetween this change and the environmental nutrients. Laboratory simulationexperiments in the natural seawater were conducted to research consumption,transformation and release of carbon, nitrogen, phosphorus and sulfur by U.and investigate the influence by these processes in the green tide on the Yellow Seaecosystem.The chemical composition and pigments in U. prolifera from different coastalarea in the Yellow Sea were determined and the impact on the color and pigment bynutrients were studied. The results showed that the content of the major chemicalcompositions, such as C, N, P, crude protein and crude fat etc., in thalli sampledfrom Jiangsu coastal area was obviously higher than that in thalli from Shandongpeninsula costal area. The same trend was noted with respect to the content of sixpigments (chlorophyll a, chlorophyll b, lutein, β-Carotene, neoxanthin andviolaxathin). Significant positive correlations (P<0.05) were noted betweenchlorophyll and C、N、Fe、Al、K and crude protein. Experimental results indicatedincreased pigment content (of chlorophyll a, chlorophyll b and lutein) in thalli towhich nitrate and phosphate had been added. It was also noted that, under low nitrateconditions, the addition of phosphate had no impact on the pigment content of thalli.Results also indicated major changes in green color of thalli (from dark to light) andthe content of chemical composition and pigments during the green tide driftingfrom Jiangsu coastal area to Shandong peninsula costal area. A change in nutritionalstatus, from rich to poor, was also noted. The physiological state transition of U.prolifera in the yellow sea was closely related to the distribution of the nutrients inone of environment factors.The consumption of biological elements by U. prolifera at different growthstages was researched to show that in the high biomass group (2.5g/L) of adult thalli,the DIN and DIP consumption from seawater in one day was approximately70% and25%, respectively. In the same group, the DIC and DIS consumption fromseawater in one day was approximately42%and1%, respectively. No significantdifference between floating and attached thalli for average DIN and DIPconsumption from seawater was observed (p>0.05). However, a significantdifference between floating and attached adult thalli was noted for daily growth rate(p<0.05). The NH4+and PO43-consumption in the fixation stage was significantlyhigher than that in the germination stage (p<0.05). In the green tide the high DINand DIP consumption by thalli could reduce the concentration of nitrogen andphosphorus nutrients in the seawater. The DIC and DIS consumption by thallicouldn t obviously impact on the seawater environment.Experiments were conducted to compare the absorption of nitrogen andphosphorus nutrient by U. prolifera in flowing-water and non-flowing water systemand study the transformation of biological elements by U. prolifera. The resultsshowed that DIN, DIP and DOP in seawater was absorbed by U. prolifera, but DONwas released in2days in the experimental system with the no-flowing water. Thallicould convert DIN to DON. DIN, DIP, DON and DOP in seawater was all absorbedby the thalli in the flowing water experiment. The average absorption rates were10.87μmol·g-1·d-1,2.41μmol·g-1·d-1,0.183μmol·g-1·d-1and0.023μmol·g-1·d-1,respectively. The transformation efficiency of inorganic form into organic form of N,P, C and S were97.33%,99.99%,96.84%and95.31%, respectively. U.prolifera inthe green tide could transform inorganic nutrients into organic nutrients, andtransport them to the Shangdong coastal area.In simulation experiments of the U. prolifera decomposition, the results showedthat the decomposed thalli mainly released organic nutrients. The highestconcentrations of organic carbon, organic nitrogen and organic phosphorus nutrientsincreased to1.65mmol/L,80.71μmol/L and1.605μmol/L, which were about3-9times higher than the initial concentrations. The TN concentration was over watereutrophication standards. However, the concentration of ammonia nitrogen (NH4+-N)was higher than the initial, about2.46μmol/L. The concentration of sulphur nutrientsincreased slightly, which couldn t impact on the environment. The dissolved oxygen was lower than4mg/L in the seawater with2.5g/L thalli after17th day, and theseawater with5g/L thalli was in the hypoxia state for a longer period. The pH valuewas less than7.5after12days. The dissolved oxygen and pH was in grade IV after17days. The green tide decomposition had obvious harmful effect on theenvironment.From what has been discussed above, the large green tide outbreaks ofU.prolifera had important influence on the migration and transformation ofbiological elements in the Yellow Sea. The total absorbed dose of nitrogen,phosphorus, carbon and sulfur by U. prolifera of huge biomass in the flourishingperiods was estimated to be360thousand tons,23.2thousand tons,400tons and16thousand tons respectively. The amount of biological elements absorbed by U.prolifera in the Jiangsu coastal area was transported to the seawaters of theShandong coastal area following current drift. The nutrients consumption by thegreen tide accounted for fewer than15%of the annual emissions of ammonianitrogen in Jiangsu province, which didn t significantly reduce the nutrients level inthe Jiangsu coastal area with seawater eutrophication. However, the high nutrientsconsumption (79%/d and36%/d) reduced the nutrients level to lower in theShandong peninsula southern seas with low nutrients, which may go against otherprimary producers, such as the growth of phytoplankton and reduce the chance ofred tides. The demise and decomposition time of green tide was about80daysduring the sinking of thalli in the shandong peninsula coastal waters, and releasedalmost all its nutrients into the sea, which may change the original nutrientsproportion in the seawater, for example, the percentage of organic nutrients ratiorised from about25%to more than90%, and cause the nutrients levels higher inShandong peninsula coastal area (TN concentration was higher than80μmol/L) andcause seawater hypoxia (DO less than4mg/L). It may play an important role on thenutrients re-distribution in that sea for nutrients absorption, migration and re-releaseby the large green tide in the Yellow sea, which could also cause the correspondingecological effects.更多还原