北部湾北部海域营养盐的分布特征及其对生态系统的影响研究

发布时间：2018-01-08 18:07

本文关键词：北部湾北部海域营养盐的分布特征及其对生态系统的影响研究　出处：《厦门大学》2014年硕士论文　论文类型：学位论文

【摘要】：北部湾是我国东南沿海一个天然的半封闭海湾,位于南海西北部。该海域处于泛北部湾区域经济合作区,近年来受城镇化、工业化和农业活动的影响显著,面临的水环境压力越来越大。为了制定更合理、科学的控制营养盐排海总量方案和海洋环境质量评价体系,需要系统地研究北部湾营养盐的分布、循环和结构特征,客观评估北部湾富营养化状况和承受的压力强度。于2011年4月和8月,在北部湾北部海域进行了2个航次的调查,测定了各种水文、化学和生物要素。调查结果表明,氮营养盐在琼州海峡入口处和防城港附近海域浓度较高,春季在海南岛西北部甚至超标,春季溶解无机氮(DIN)、总溶解态氮(DN)和总氮(TN)的平均含量分别为7.93μmol/L、21.9μmol/L和28.9μmol/L,夏季分别为2.54μmol/L,11.5μmol/L和16.8μmol/L。活性磷酸盐(SRP)在春夏的平均含量均为0.06μmol/L,低于浮游植物生长阈值,且营养盐比值均偏离Redfield值,因此磷成为该海域营养盐绝对和相对限制因子。春季溶解态硅酸盐(DSi)的含量为2.12μmol/L,夏季有径流输入补充,增加至5.18μmol/L。广西近岸港湾的营养盐在1990～2010年期间浓度呈上升趋势,特别是氮。春季水体中DIN的主要形态为硝酸盐(N03-N),比例达55.0%,夏季为铵盐(NH4-N),占49.8%；DN和总溶解态磷(DP)都以溶解有机态为主,分别占63.8%-77.8%和77.0%-88.5%；TN主要存在形式是溶解态,而总磷(TP)在春季以颗粒态为主,夏季以溶解态为主,因此溶解有机态营养盐在该海域的生态系统中有着重要作用。通过分析该海域的氮磷循环特征,发现其水体的生物化学自净能力春季强于夏季。用单项指标和综合指数法评估营养盐对各区域的压力强度的结果发现,廉州湾(南流江口)承受的压力强度最大,琼州海峡入口处和防城港附近海域的压力次之；对溶解有机态含量高、无机态含量低于浮游植物生长阈值的海湾,用潜在性富营养化水平评价模式评估时,应选择总溶解态的含量而非溶解无机态,研究海域评估结果为中度营养、春季存在磷限制；用压力—状态—响应模式进行的半定量评估结果表明,营养盐对海域的压力强度为中等。对调查数据进行的主成分分析表明,影响北部湾北部海域生态环境的关键因子是溶解氧(DO)和DN,氮营养盐对海域生态环境的压力最大；关键区域在琼州海峡入口处的海南岛西北部和涠洲岛东南部海域,防城港附近海域次之；春季是关键季节,需要控制氮的输入,夏季次之,但要注意控制磷的含量。
[Abstract]:Beibu Gulf is a natural semi - closed bay along the southeast coast of China . It is located in the north - west of South China Sea . The sea area is in the area of Pan - Beibu Gulf region economic cooperation . In recent years , it has been affected by the urbanization , industrialization and agricultural activities . The water environment pressure is increasing . In order to formulate more reasonable and scientific control nutrient salt discharge quantity scheme and marine environment quality evaluation system , it is necessary to study the distribution , circulation and structural characteristics of nutrient salt in Beibu Gulf , and objectively evaluate the eutrophication status and pressure intensity of Beibu Gulf . The average contents of dissolved inorganic nitrogen ( DIN ) , total dissolved nitrogen ( DN ) and total nitrogen ( TN ) in spring and summer were 7.93 渭mol / L , 21.9渭mol / L and 16.8渭mol / L , respectively , and the average contents of dissolved inorganic nitrogen ( DIN ) , total dissolved nitrogen ( DN ) and total nitrogen ( TN ) in spring and summer were 2.54渭mol / L , 11.5渭mol / L and 16.8渭mol / L , respectively . The main form of DIN in spring water is nitrate ( N03 - N ) , the proportion is 55.0 % , the sum of summer is ammonium salt ( NH4 - N ) , accounting for 49.8 % ; DN and total dissolved phosphorus ( DP ) are mainly dissolved organic states , respectively 63.8 % - 77.8 % and 77.0 % - 85.5 % ; TN mainly exists in the form of dissolved state , and total phosphorus ( TP ) is mainly dissolved state in spring , so the dissolved organic nutrient salt plays an important role in the ecosystem of the sea area . The results of the assessment of the pressure intensity of nutrient salts on each region by single index and comprehensive index method show that the pressure intensity of the Lianzhou Bay ( Nanliujiang estuary ) is the highest , and the pressure of the sea area near the entrance of Qionghai Channel and the coastal area of Fangchenggang is the second . The content of the total dissolved state and the non - dissolved inorganic state should be selected in the assessment of the potential eutrophication level . The semi - quantitative evaluation results of the pressure - state - response mode indicate that the pressure intensity of the nutrient salt on the sea area is medium . The main components of investigation data show that the key factors that affect the ecological environment in the northern part of Beibu Gulf are dissolved oxygen ( DO ) and DN , the nitrogen nutrient salt is the biggest pressure on the ecological environment of the sea area . The key area is the sea area near the port of Hainan Island and the south - east of Weizhou Island . The spring is the key season . It needs to control the input of nitrogen and the next time in summer , but pay attention to controlling the content of phosphorus .

【学位授予单位】：厦门大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P734.44;X171

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