【作者】 王伟；

【导师】 石晓勇； 梁生康；

【作者基本信息】 中国海洋大学 ， 化学工程（专业学位）， 2013， 硕士

【摘要】 近年来，随着全球气候变化和人类活动的加剧，强降雨等极端气候事件频发，对近海生态环境的影响不容忽视。强降雨不仅可导致短时间内盐度、浊度等海洋物理环境的剧烈改变，而且大量陆源物质通过径流和大气沉降输入近海水体中，造成短时间内海区营养物质含量迅速升高，富营养化程度显著增大，对近海生态环境可能造成诸多不利影响。因此，客观、准确的认识和把握强降雨过后近海水体主要水文、化学和生物因子的变化情况，研究强降雨过程对近海生态系统营养盐补充和浮游生物生长状况的短时间尺度影响，明确近海生态环境对强降雨的响应关系，这对于阐明给您强降雨近海生态环境所带来的危害具有重要意义。本文以胶州湾这一典型半封闭海湾作为研究对象，以2012年8月2日～8月3日台风“达维”给青岛地区带来的强降雨事件为背景，通过降雨前后生源要素陆源输入、大气湿沉降和海上分布同步调查，结合围隔生态系统试验，考察强降雨对胶州湾生源要素特别是营养物质的补充及其分布和结构的影响，并结合其他环境因子的变化，初步探讨强降雨对胶州湾浮游植物生物量和种群结构的影响及其机制，主要结论如下：1、通过对比分析强降雨前后生源要素输入通量的变化，确定了河流的陆源输入和大气湿沉降对胶州湾主要生源要素补充作用。（1）该次强降雨导致的陆源PO₄-P、SiO₃-Si、DIN的输入通量分别达到91.07×10³mol/d、1002.03×10³mol/d和439.13×10⁴mol/d，分别为同期非降雨期输入通量的24倍、18倍和2倍，而强降雨过程中通过大气湿沉降输入胶州湾的DIN、 PO₄-P、 SiO₃-Si的通量分别达到81.29×10⁴mol/d、60.22×10³mol/d和67.27×10³mol/d。（2）降雨前后河流输入的DIN组成也发生明显变化，降雨前NO₃-N为DIN主要组分，占比高达75%，而在降雨过程中，NO₃-N占DIN比例逐步下降，NH₃-N占DIN比例则逐渐升高，达到70%，而大气湿沉降中DIN中以NH₃-N为主，占比达76%。（3）悬浮颗粒物（SS）、活性磷酸盐（PO₄-P）含量变化过程受降雨影响持续时间较短，响应较快。DIN、SiO₃-Si含量变化过程受降雨影响持续时间较长，响应较慢。2、应用2012年7和8月在降雨前、降雨后1d和降雨后18d进行的3个航次的现场调查数据，分析了强降雨前后对胶州湾环境因子、生源要素和浮游植物生物量和群落结构的变化。（1）强降雨导致胶州湾悬浮颗粒物（SS）含量升高、盐度显著下降、温度明显增大、pH值明显降低和溶解氧（DO）显著下降。其中，强降雨1d后，整个湾内SS的平均值达到12.75±5.80mg/L，较降雨前提高18.5%，盐度平均值为28.31±1.75，较降雨前降低5.8%，pH平均值为7.82±0.13，较降雨前的7.99±0.18有所降低，DO平均值为4.4±0.33mg/L，较降雨前下降24.9%；而降雨后18d，胶州湾内上述各项水文和理化参数基本恢复到降雨前水平。（2）强降雨导致胶州湾生源要素的水平和结构发生明显变化。尽管降雨前后生源要素DIN、PO₄-P、SiO₃-Si基本都呈现湾底高、湾中央和湾口低的分布特征，但降雨后1天，胶州湾生源要素DIN、PO₄-P、SiO₃-Si含量较降雨前显著升高，平均值分别达到37.90±26.72μmol/L、1.75±1.28μmol/L和20.18±17.22μmol/L，较降雨前分别提高54.8%、127.3%和144.6%。降雨过后18天，各生源要素含量基本恢复到降雨前水平。从营养盐结构来讲，降雨前DIN/PO₄-P值呈现明显的斑块状不均匀分布，高值区存在于大沽河、李村河河口附近，其值在12.89～181.66范围内，平均为41.37±39.79，远高于Redfield比值，而降雨后DIN/PO₄-P斑块状分布基本消失，其值显著降低，在11.67～29.31范围内，平均为21.13±4.17，接近Redfield比值，表明限制的状况有所缓解；同样，降雨前SiO₃-Si/DIN值呈现河口区和近岸高，湾中央低的分布趋势，其值在0.07～0.57范围内，平均为0.31±0.14；降雨后SiO₃-Si/DIN值受陆源输入影响，呈现由湾底部到湾口逐渐降低的趋势，其值在0.30～0.74范围内，平均为0.49±0.13，较降雨前提高58%。进一步应用富营养化指数（E）分析表明，降雨前，胶州湾大部分海域E值接近1，处于富营养化临界状态。强降雨后1d，胶州湾富营养化程度较降雨前大大提高，E>1的富营养化区域面积占比达到70%，而E>5的严重富营养化区域面积占比达到50%，整个海域E平均值达到13.71±21.20，较降雨前提高215%；而降雨后18天，富营养化程度大大降低，但仍稍高于降雨前水平。（3）Chl a含量和网采浮游植物细胞丰度的数据显示，强降雨1d后胶州湾浮游植物生物量明显降低，浮游植物优势种发生显著变化。其中，降雨后1天Chl a平均值和浮游植物细胞丰度平均值分别为0.587±0.579μg/L和1.6×10⁶cells/m3，较降雨前分别降低了82.8%和94.8%；降雨后，胶州湾甲藻丰度占比较降雨前升高，而硅藻丰度占比较降雨前减小；同时一些外洋性和噬氮性浮游植物优势种减少，而温带暖水性浮游植物增多。3、通过在胶州湾海水中添加降雨后的大沽河口水的围隔生态实验，考察了不同强度降雨下的河流输入对胶州主要水文要素和生物、化学要素的影响。取胶州湾中央站位的现场海水，其盐度为30左右，其中M1围隔袋中添加此现场海水作为对照组，其余三组围隔袋M2、M3和M4添加不同比例的现场海水和大沽河入海口河水，分别调节其盐度为28、26、24左右，以模拟不同降雨强度下胶州湾的海水。在7d的实验周期内，4个围隔袋中，DIN、PO₄-P、SiO₃-Si含量都呈现逐步下降的趋势，但添加河水的围隔袋中营养盐含量显著高于对照组；而对照组M1、盐度为28的M2和盐度为24的M4围隔袋中Chl a均呈现先略有增加后快速下降然后又增加再降低的波动变化趋势，但整体维持在0.41～2.77μg/L的较低水平，而盐度为26的围隔袋中则在培养第5d时出现快速增长趋势，Chl a最高值达3.35μg/L，表明此盐度梯度下的条件较有利于浮游植物的生长繁殖。4、依据强降雨前、后现场调查和围隔生态实验结果，应用相关性分析、主成分分析和聚类分析等统计学方法，综合分析强降雨对胶州湾浮游植物生物量和浮游植物种群的影响。强降雨导致胶州湾生源要素输入强度显著增大，大大提高了胶州生源要素的含量，深刻改变了生源要素的结构，为浮游植物的爆发性生长提供了充足的物质基础，但同期由于大量淡水输入导致的水动力条件的改变却不适宜浮游植物的生长，浮游植物丰度较降雨前大大降低，浮游植物种群结构发生明显变化。进一步分析表明，强降雨后局部海域温度的升高可能是暖水性浮游植物如波状石丝藻（Lithodesmium undulatum Ehrenberg）成为优势种的主要原因；海水盐度的降低，是外洋性浮游植物减少、近岸性种呈增加的重要原因；降雨后胶州湾海水中DIN/PO₄-P值降低、SiO₃-Si/DIN值升高，可能是浮游植物中的嗜氮性藻减少的主要原因。更多还原

【Abstract】 Typhoon-induced precipitation events occur frequently, they have animmeasurable impact on coastal ecosystem, and have brought adverse factor ofcoastal economic society and economic development. Therefore it has importantsignificance that understanding and grasping the changes of hydrological, chemicaland biological factors about offshore environment after the rain, discussing theinfluence of heavy rainfall process on the supplements of the nutrient and the growthof phytoplankton on the offshore ecosystem.Based on the torrential rain in Qingdao by the influence of typhoon "davey" asthe research background, Jiaozhou Bay as the research object, and through a numberof sampling trips in Jiaozhou Bay and major rivers emptied into the bay, mesocosmexperiment and other means to realize the research that a series of changes about thesupplementary of the biogenic elements and the growth condition of phytoplanktonafter the rain. The main results are as follows:1、According to a number of sampling trips in major rivers emptied into theJiaozhou Bay and the rainfall data collected in the process of rain, the results showthat the content changes of SS and PO₄-P is shorter duration and faster response thanDIN and SiO₃-Si in the process influenced by the rainfall. While the composition ofDIN is changing around the rainfall （before the rainfall, NO₃-N/DIN up to75%, withthe occurrence of rainfall, NO₃-N/DIN decreased, NH₃-N/DIN increased gradually,and finally a combination of both became the main component of the DIN）. The inputof PO₄-P and SiO₃-Si caused by land source rainwater was significant, the fluxes ofPO₄-P、 SiO₃-Si caused by land source rainwater to the Jiaozhou Bay were91.07×10³mol/d and1002.03×10³mol/d which were respectively24times and18times over the same period without rainfall. The atmosphere wet deposition fluxes of DIN, PO₄-P and SiO₃-Si were81.29×10⁴mol/d,60.22×10³mol/d,67.27×10³mol/dduring the rainfall.2、Based on the data in July, August of2012, the supplement and distribution ofthe biogenic elements influenced by the rainfall was analysed.（1） Compared with those before the rainfall, biogenic elements were significantlyhigher after the rainfall in the Jiaozhou Bay.18days after the rainfall, the high valuearea of the five nutrients was in the northeastern part of the gulf, other regionsrecovered to the level before the rainfall.（2） Before the rainfall, there were potential limitation of PO₄-P in Dagu RiverEstuary and Licun River Estuary, SiO₃-Si may be limited or potentially limited in thecenter of the bay. One day after the rainfall, the nutrients throughout the bay were notlimited except the bay estuary.18days after the rainfall, PO₄-P was a potentiallimiting factor in the middle of the bay, the proportion of SiO₃-Si/PO₄-P andSiO₃-Si/DIN were conducive to the growth of diatoms throughout the bay.（3） Before the rainfall, the lower degree of eutrophication occurred mainly in thenorth of the Tuandao and Dagu River Estuary connection, and increasing gradually tothe northeast. One day after the rainfall, the eutrophication area was further increased,only the estuary of the bay did not reach eutrophication level.18days after the rainfall,eutrophication was slightly higher than the level before the rainfall, most areas wereclose to1that means it is in a eutrophication critical state.3、Through the ecological mesocosm experiment, it achieves a live simulation ofthe changes of the hydrological, biological and chemical factors after the rainfall inJiaozhou Bay. Chl a showed the variation of increasing at first, then decreasing in thefour bags which have different salinity gradient. The Chl a of M3appeared to rapidgrowth after reduced, this salinity may be more favorable to the growth andreproduction of phytoplankton. But overall there are some differences between thephenomena of the mesocosm experiments and the results of field survey, mesocosmexperiments can not simulate live marine conditions completely.4、The results of principal component analysis about the main environmentalfactors affecting the growth of phytoplankton can be seen before and after the rainfall, rainfall was the main reason for changes in the structure of the principal componentabout environmental factors. And18days after the rainfall, the principal componentof the main environmental factors was back to the state before the rainfall, nutrientsand salinity had always been the main environmental factors affecting the growth ofphytoplankton. The total species and total abundance of phytoplankton had decreasedsignificantly, also changed in the number and structure of the dominant species（inshore species increase, oceanic species decrease）.更多还原