海洋酸化与海岸带生源要素和微量元素归趋及形态的相互作用研究
其他题名环境地球化学
张锦峰
学位类型博士
导师高学鲁
2016-07
学位授予单位中国科学院大学
学位授予地点北京
学位专业环境科学
关键词海洋酸化 生源要素 微量元素 归趋 形态 相互作用
其他摘要
       除海洋碳系统之外,海洋中的有机和无机化学环境将大范围地受海洋酸化的影响。与碳化学受酸化影响相似,海水中存在酸碱平衡的其他弱酸也将受到CO32-浓度降低、 HCO3-浓度增加以及溶解态CO2浓度增加的影响。酸化将引发这类物质进行与pH值降低相关的形态转化和介质迁移。但关于海洋酸化对海洋生态系统中重要元素形态和归趋影响的研究还很少。因此,研究生源要素和微量元素形态和归趋对海洋酸化的响应及作用机制,以及他们在未来高CO2海洋环境中的地球化学特征是非常必要的。本学位论文设计并模拟不同程度的海水酸化(pH ≈ 8.0、7.5、7.0),研究了不同程度酸化前后上覆海水、间隙水、沉积物及悬浮颗粒物中几种生源要素(C、N、P、Si)和微量元素(Pb、Ni、Sc、V、Cd、Mn、Fe、Cu、Zn、Hg、As、Cr)浓度和赋存形态的变化规律,探讨了海水-沉积物系统中生源要素和微量元素形态和归趋对酸化的响应机制,并通过对莱州湾西南部海岸带水体中生源要素和pH的调查,考察了实际海岸带体系中生源要素与酸化的相互作用关系,通过对莱州湾潮间带沉积物中微量元素(Cd、Cr、Cu、Hg、Ni、Pb、Zn、As)的调查,考察了莱州湾潮间带沉积物重金属污染状况,分析预测了酸化对莱州湾潮间带沉积物重金属污染状况的影响,获得了一系列新的结果和认识。
        海水酸化可能促使更多的营养盐从体系的其他介质迁移到上覆水中。模拟酸化导致上覆水中总氮(TN)、氨氮(NH4-N)、总磷(TP)、活性磷酸盐(PO4-P)、溶解态硅酸盐(DSi)含量增加,从pH≈8.0降低到pH≈7.0,增加的最大幅度分别为:27.7%、48.8%、153%、23.6%和13.1%,分别在模拟实验的第1 d、30d、60 d、7 d和30 d达到,而使硝态氮(NO3-N)含量降低;随酸化时间延长上覆水中TN 含量总体呈减少趋势,说明酸化对上覆水中氮的影响随时间延长减弱;随酸化程度增加和酸化时间延长,上覆水中的溶解态硅酸盐(DSi)含量持续增加,说明酸化对上覆水中硅的影响随时间延长增强。
       间隙水中TN、NH4-N和DSi含量随酸化增加,而NO3-N、NO2-N、TP和PO4-P含量随酸化降低,从pH≈8.0降低到pH≈7.0,降低幅度分别在模拟实验的第30 d、30 d、60 d和60 d达到最大值分别为:40.2%、79.6%、83.8%和93.2%;说明酸化导致更多的NH4-N和DSi迁移到间隙水,而使NO3-N、NO2-N和PO4-P从间隙水迁出。
        从pH≈8.0降低到pH≈7.0,沉积物中的无机碳(DIC)、TN和TP含量随酸化降低,降低的最大幅度分别为:79.2%、26.3%和13.9%,分别在模拟实验的第15 d、1 d和7d达到,说明酸化促进了它们从沉积物中的迁出;程度为pH≈8.0的酸化对沉积物中的磷含量影响不大,但随酸化程度加剧,沉积物中松散结合态磷、铁结合态磷和自生态磷含量随酸化降低,它们受酸化影响大小顺序为:自生态磷 > 铁结合态磷 > 松散结合态磷。
悬浮颗粒物中的DIC含量随酸化降低,在模拟实验进行的第1 d就达到最大值66.7%;TN含量在模拟酸化30 d前随酸化增加,30 d后随酸化降低,最大幅度为22.9%;而TP、无机磷(IP)和生物可利用磷(BiaP)含量随酸化增加,增加量随时间变化基本呈先增加后减少趋势,说明酸化可能导致更多的磷迁移到悬浮颗粒物中。
海水酸化可能导致沉积物中的Fe和Mn向上覆水溶出,溶出最大量可分别达到48.2%和45.9%。Fe和Mn的溶出可能导致在沉积物中与铁锰氧化物结合存在的大部分元素含量降低。沉积物中V、Zn、Pb、As、Cr和Cu的含量随酸化降低,中长期酸化(> 15 d)对各元素含量影响的大小顺序大致为:As > Fe > Mn > V > Cr > Zn > Pb > Cu;沉积物中Ni和Co的含量随酸化增加,影响大小顺序为:Co > Ni;沉积物中Sc和Cd的含量对酸化不敏感;模拟酸化对沉积物中的Ca和Μg含量影响不大,可能会导致Na含量有所降低;短期酸化(<7 d)可能使沉积物中Al含量有所升高,而中长期酸化可能导致沉积物中Al含量减少。
       悬浮颗粒物中Zn、Mn、V、Ni和Sc的含量随酸化降低,中长期酸化(长于15 d)对各元素含量影响大小顺序大致为:Ni > Zn > Mn > Sc > V;悬浮颗粒物中Fe和As含量随酸化增加,影响大小顺序为:Fe > As;悬浮颗粒物中Pb、Cr、Cu、Co和Cd含量对酸化不敏感。各种微量元素的不同赋存形态受酸化影响各不相同,多数元素的酸可溶态和可还原态受酸化影响较大。
        营养盐含量的增加,特别是DIN和DSi含量的增加可能加剧莱州湾西南海岸带水体的酸化,该区域的酸化对营养盐结构变化不敏感。
       莱州湾西南岸潮间带表层沉积物中As、Cr、Cu、Ni、Pb和Zn处于无污染和低生态风险状态;而Cd和Hg处于中度污染和中度到中高等风险状态。酸化可能影响莱州湾海岸带沉积物重金属的污染状况,导致某些重金属从沉积物溶出,对该区域Cd和Hg的影响值得引起关注。
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      An important but be underestimated consequences of Ocean acidification is changing the large scale of inorganic and organic chemical environment in addition to ocean carbon system of the Ocean. Similar to the carbonate chemical system, detected CO32- concentration reducing cause the concentration of HCO3- and dissolved CO2 increasing, also will lead to morphological transformation of the other weak acid associated with lower pH in acid-base balance. Knowledge about the effects of ocean acidification on fate and morphology of important elements in Marine ecosystem is rather scarce. So drawing out the effects and function mechanisms of Ocean Acidification to fate and morphology of matriculate elements and trace elements, and research geochemical characteristics of these elements in the future high CO2 concentration environment are very necessary. This research design and simulation of different level of ocean acidification (pH≈8.0, 7.5 and 7.0) in lab scale tanks, study the concentration and morphology changes of several nutrient elements (C, N, P, Si) and trace elements (Pb, Ni, Sc, V, Cd, Mn, Fe, Cu, Zn, Hg, As, Cr) before and after different levels of acidificstion in overlying waters, pore water, sediment and suspended particulate matter, and inguiry the mechanisms of these changes. Explore the effects of ocean acidification to nutrient and trace elements in water/sediment system of shallow water. In addition, according to the survey of nutrient and pH in the southwestern Laizhou bay, investigate the interaction relations between acidification and nutrient in practical environment of coastal zone; and according to the survey of trace elements (Cd, Cr, Cu, Hg, Ni, Pb, Zn and As) in sediments from intertidal zone of the southwestern Layzhou bay, examine heavy metal pollution status of the sediments, analysis and predict the effect acidification to heavy metal pollution status in sediment from intertidal zone of the southwestern Laizhou bay.
        The concentration of total nitrogen (TN), ammonia nitrogen (NH4-N), total phosphorus (TP), activated phosphorus (PO4-P) and dissolved silicate (DSi) in the overlying water increase with acidification, and with pH decreasig from 8.0 to 7.0, their biggest increaments reached 27.7%, 48.8%, 153%, 23.6% and 13.1%, respectively, in the simulation experiment day 1, day 30, day 60, day 7 and day 30, respectively, but the content of nitrate nitrogen (NO3-N) decrease with acidification; With the extension of acidification time the TN content showed a trend of decrease in overlying water, indicated that the influence of acidification to nitrogen in overlying water weakened with the extension of acidification time; with the degree of acidification increased and acidification prolonged, DSi content in overlying water increasing, illustrated that  the effects of acidification to silicon in overlying water increase with the extension of time.
        The concentration of TN, NH4-N and DSi in porewater increased with acidification, The concentration of NO3-N, NO2-N, TP and PO4-P decreased with acidification, with pH decreasig from 8.0 to 7.0, their maxmum reduction reched 40.2%, 79.6%, 83.8% and 93.2% in day 30, 30, 60 and 60, respectivly; Acidification caused more ammonia nitrogen and silicate migrated to the pore water, and precipitation nitrate, nitrate and phosphate from pore water.
        With pH decreasing from 8.0 to 7.0, the concentration of inorganic carbon (DIC), TN and TP in sediments decreased, the maxmum reduction reched 79.2%, 26.3% and 13.9% in day 15, 1 and 7, respectively, indicating that acidification promoted they separating out from sediments; Lower degree of acidification(pH ≈ 8.0) can not cause big change in phosphorus content of the sediment, but a little higher degree of acidification (pH < 7.5) could decrease the concengtration of loose combining phosphorus, iron combining phosphorus and authigene phosphorus in the sediment, the order of the influencing was: Authigene P > iron combining P > loosely combining P.
        DIC content in the suspended particulate matter decreased with acidification and reched the maxmum 66.7% in day 1; TN content in the suspended particulate matter increased with acidification before 30 days and reched the maxmum 22.9% in day 30, but after 30 days TN content decreased with acidification in the suspended particulate matter; The concentration of TP, inorganic phosphorus (IP) and bioavailable phosphorus (BiaP) increased with acidification, suggested that acidification could lead to more phosphorus migration into the suspended particulate matter.
        Acidification can result in Fe and Mn dissolution from the sediments, and the maxmum amounts reached 48.2% and 45.9%, respectively. And then the elements combined with Fe/Mn oxides may dissolution from sediments with Fe and Mn dissolution. V, Zn, Pb, As, Cr and Cu content in sediments decreased with acidification, the order of influence degree of medium and long-term acidification (>15 days) on these element is roughly about: As > Fe > Mn > V > Cr > Zn > Pb > Cu; The content of Ni and Co in the sediments increased with acidification, the influence order was: Co > Ni; Sc and Cd content in the sediments are not sensitive to acidification; Acidification seemingly could not influence the content of Ca and Μg in sediments, but may lead to decreasing of Na content; Short-term acidification (<7 days) may make Al content increaseing in the sediments, while the medium and long-term acidification may reduce Al content in sediments.
         The concentration of Zn, Mn, V, Ni and Sc in suspended particulate matters decreased with acidification, the order of influence degree of medium and long-term acidification (>15 days) on these elements was roughly about: Ni > Zn > Mn > Sc > V. The content of Fe and As in suspended particulate matter increased with acidification, the influence order was: Fe > As; Pb, Cr, Cu, Co and Cd in suspended particulate matters were not sensitive to acidification. Different forms of the elements demenatrated different responses to acidification.
       Increasing nutrient content in surface water, especially increasing the concentration of DIN and DSi may intensified acidification in the water system of coastal laizhou bay, acidification of that region is not sensitive to the nutrient structures.
       As, Cr, Cu, Ni, Pb and Zn in intertidal surface sediments from the southwest coast of laizhou bay were in status of no pollution and low ecological risk; But Cd and Hg were in moderate pollution status and moderate to high ecological risk status. Acidification is likely to affect the heavy metal pollution status in sediments of laizhou bay coastal zone by separating some heavy metals from sediment. The influence of acidification to Cd and Hg in that region deserved attention.
语种中文
文献类型学位论文
条目标识符http://ir.yic.ac.cn/handle/133337/13824
专题中国科学院烟台海岸带研究所知识产出_学位论文
作者单位中国科学院烟台海岸带研究所
第一作者单位中国科学院烟台海岸带研究所
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张锦峰. 海洋酸化与海岸带生源要素和微量元素归趋及形态的相互作用研究[D]. 北京. 中国科学院大学,2016.
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