【作者】 郑爱榕；

【导师】 李文权；

【作者基本信息】 厦门大学 ， 海洋化学， 2009， 博士

【摘要】 本文以光合细菌、天然菌群、海洋薇藻为生物对象，研究不同水体、不同粒径和有机碳浓度不同的胶体对生物生长的影响，同时测定了福建九龙江河口海区河水、河口水和海水的氮、磷、铁、氨基酸和碳水化合物在真溶液和胶体中的含量和分布，以期探讨天然胶体对生物的可利用性及其与胶体化学组成的关系，了解天然胶体对生物生长影响的机制。主要研究结果如下：1．在九龙江河口海区调查期间，河水、河口水和海水中的无机氮、各种形态磷和Fe³⁺主要分布在真溶液（＜10 kDa）中，有机氮和Fe²⁺主要分布在胶体（10kDa～0.22μm）中；在真溶液和胶体中，各种形态的氮和总铁的含量从河流至海洋依序递减；真溶液中的Fe²⁺在河口区最低，胶体中的Fe²⁺在河口最高。2．在九龙江河口海区调查期间，海水中的可水解氨基酸（THAA）和碳水化合物（CHO）主要存在于真溶液中，在河口水和河水THAA主要存在于胶体中，CHO主要存在真溶液中。三种水体中胶体的氨基酸组成最齐全，达16种，优势组成依序是甘氨酸+苏氨酸、天冬氨酸、谷氨酸、丙氨酸+酪氨酸；三种水体中胶体的中性醛糖组成相似，葡萄糖和半乳糖占优势。3．海水胶体对光合细菌（PSB）的生长有显著的促进效应，在适宜PSB生长的条件下，粒径为10 kDa～0.22μm的海水胶体，其相对增长率平均可提高11.3％～22.6％，对PSB生长的促进作用大于粒径为1 kDa～10 kDa的海水胶体。有机碳浓度不同的三种胶体对PSB的相对增长率平均值Y为3.6％～196.2％，对天然菌群的Y值为48.4％～133.9％，Y均与有机碳浓度无相关关系；河水胶体对PSB生长的促进作用＞＞海水胶体＞河口水胶体。高分子量的海洋胶体可以提高PSB单不饱和脂肪酸C_16∶1和C_18∶1和高度不饱和脂肪酸C_20∶4的含量。4．海洋胶体对海水小球藻、亚心形扁藻和球等鞭金藻的生长有明显的促进作用，在有机碳浓度为4.8μmol／L～238.4μmol／L、粒径为10 kDa～0.22μm的海水胶体中，其增长率的平均值Y为2.9％～28.9％，与有机碳浓度相关。粒径为10 kDa～0.22μm的海水胶体对三种海洋微藻的促进作用是粒径为1 kDa～10 kDa的海水胶体的1.2～1.9倍，表明高分子量胶体的生物活性高于低分子量胶体。河水胶体对海水小球藻的促进作用＞河口水胶体。胶体中N、P和Fe同样对三种微藻的生长有促进作用，增长率的平均值Y为19.3％～498.5％，其中胶体Fe对球等鞭金藻和亚心形扁藻的效应比胶体N和P约大6～7倍，而胶体N和P对海水小球藻的促进作用则约比胶体Fe大3倍。5．天然胶体对海洋微藻脂肪酸组成的影响因藻而异。海水小球藻和亚心形扁藻的脂肪酸在真溶液（＜10 kDa）的培养介质中含量最高，球等鞭金藻脂肪酸在胶体有机碳浓度为119.2μmol／L的海水胶体（粒径为10 kDa～0.22μm）培养介质中最高。粒径为10 kDa～0.22μm的海水胶体介质中的海水小球藻、球等鞭金藻的脂肪酸含量大于粒径为1 kDa～10 kDa的海水胶体，而亚心形扁藻的脂肪酸含量相反。海水小球藻在河水胶体中的饱和脂肪酸含量大于在河口水胶体，不饱和脂肪酸含量小于河口水胶体。三种微藻的总不饱和脂肪酸含量，在以海洋胶体为惟一N源介质中最高，以海洋胶体为惟一P源介质中次高，以海洋胶体为惟一Fe源介质中最小。更多还原

【Abstract】 Colloids generally refer to microparticles, macromolecule or macromoleculepolymers, of which molecular weights range from 1 k Dalton to 100 k Dalton, orparticle size between 1 nm to 1μm. They widely exist in natural fresh water orseawater environment and origin mainly from terrigenous river input, resuspendedseawater sediment and biological metabolism process in water column. Besides,colloidal organic substance can also be produced by the transformation of particleorganic substance during biological or non-biological processes. Therefore naturalcolloid mainly contains organic polymer（such as polyoses, protein, polypeptide, fulvicacid and cell chippings） and inorganic particle（such as iron oxides, manganese oxides,silicon dioxide and clay minerals）, as well as living body（bacteria and virus）. Becauseof the small size, huge specific area and abundance of organic functional group, theybecome important vector of nutritive organic carbon, nutrients, trace metal, traceorganic matter and pigment. Researches showed that growth and metabolism rate ofbacteria in the existence of high molecular weight colloids were three to six timeshigher than those of lower molecular weight colloids. Colloidal organic mattersexposed to sunshine can release bio-available nitrogen-rich components and promotebiological degradation. Dissolved organic matter is an important source ofbio-available nitrogen for coastal bacteria and phytoplankton. Increase of their contentswill promote the propagation and growth of sea algae, and lead to red tide at certainconditions. As the result, studies on chemical compositions of natural colloids and their biological effects will make significant sense for discovering the mechanism of globalclimate change and marine red-tide as well as further understanding the bioavailabilityof biogenic element and their biological effects.In our previous work, biogeochemical behavior and chemical compositions, ofmarine colloid had been studied, however, the description of chemical composition, aswell as bioavailability need to be farther proved. In this work, photosynthetic bacteria,natural bacterial community; marine algae were the targets for study of influence ofcolloids collected from different sources and with different particle size and organiccarbon content, on the growth of organism. Nitrogen, phosphorus, iron, amino acid andcarbohydrate contents in their truly dissolved phase and colloidal phase fromJiulongjiang river, Jiulongjiang estuary and seawater of Fujian, as well as theirdistribution pattern were also investigated to reveal the relationship between thechemical compositions and the bioavailability of natural colloids, and explore themechanism that how natural colloids effect the organism growth. The results are asfollows:1. In the water samples of Jiulongjiang river, Jiulongjiang estuary and XiamenBay, inorganic nitrogen, all species of phosphorus and ferric ion mainly distributed intheir truly dissolved phase（＜10 kDa）, and organic nitrogen and ferrous iron mainly incolloidal phase（10 kDa～0.22μm）, during the study period. In both truly dissolvedand colloidal phase, all species of nitrogen and total iron contents decreased fromriver-end to sea-end. Content of truly dissolved Fe²⁺ was the lowest in estuary sampleswhile contents of "dissolved" and colloidal Fe²⁺ was the highest in estuary samples.2. In the Jiulongjiang river estuary, amino acids and carbohydrate from seawatersample mainly distributed in truly dissolved phase, and amino acid from both river andestuarine water samples mainly in colloidal phase. while their carbohydrate mainly intruly dissolved phase. Colloids had 16 kinds of amino acid components from threesources. The dominance components were glycine+ threonine, aspartate, glutamic acidand alanine+tyrosine. The compositions of neutral aldose from three sources were similar with each other. Glucose and galactose were dominant components in colloidalphase.3. Marine colloids had significant enhancement effect on the growth of PSB. Withthe condition suitable for PSB, marine colloids with particle size of 10 kDa～0.22μmcan increase the relative growth rate by 11.3%～22.6%, which were higher than that ofmarine colloids with particle size of 1 kDa～10 kDa. Relative growth rates of PSB ofsamples from three sources with different organic carbon concentrations were 3.6%～196.2% on average, and 48.4%～133.9% for natural bacterial community on average,both of which had non-correlation with organic carbon concentration. Enhancementeffect for PSB of colloids of river water was much higher than that of seawater, both ofwhich were higher than that of estuarine water. Marine colloids of high molecularweigh could increase contents of monounsaturated fatty acid C_16:1 and C_18:1 andcontent of high unsaturated fatty acid C_20:4 in PSB.4. Marine colloids also had significant enhancement effect on the growth ofmarine Chlorella, Platymonas subcordiformis and Isochrysis galbana. Their averagegrowth rates were 2.9%～28.9% in marine colloids with particle size of 10 kDa～0.22μm and organic carbon concentrations of 4.8μmol/L～238.4μmol/L, havingrelationship with organic carbon concentrations. Enhancement effect of colloids withparticle size of 10 kDa～0.22μm was 1.2～1.9 times higher than that of colloids withparticle size of 1 kDa～10 kDa for these three algae, indicating that the bioactivity ofhigh molecule weights colloids was higher than low molecule weights colloids. Whatwas more, enhancement effect of river colloids on marine Chlorella was larger thanestuarine colloid.5. The influences of colloid to fatty acid components of marine algae differedfrom each alga. Fatty acid contents in Marine Chlorella and P. subcordiformis werehighest when they were cultured in truly dissolved phase while fatty acid contents in I.galbana were highest when C_COC=119.2μmol/L in kinds of culture mediums withdifferent organic carbon concentrations(C_COC) and particle size of 10 kDa～0.22μm. Fatty acid contents in marine Chlorella and I. galbana cultured in colloidal mediaswith particle size of 10 kDa～0.22μm were higher than those cultured in colloidalmedias with particle size of 1 kDa～10 kDa, but it was inversed for P. subcordiformis.Saturated fatty acid contents in marine Chlorella cultured in colloids from river waterwere higher than those cultured in colloids from estuarine water; however, theunsaturated fatty acid contents were lower. Contents of total unsaturated fatty acid inthese three kinds of algae were highest in the algae cultured with colloid as solenitrogen source and followed by the algae cultured with colloid as sole phosphorussource, while lowest in the algae cultured with colloid as sole iron source.更多还原