长江口外浮游植物死亡释放溶解有机质的降解及其溶氧消耗
|
摘要
浮游植物光合作用产生的溶解有机质(dissolved organic matter,DOM)是海洋中溶解有机质的重要来源,浮游植物死亡后释放的新鲜溶解有机质活性高、数量大、生物可利用性高,其降解过程中对溶解氧(dissolved oxygen,DO)的消耗显著。但到目前为止,对此类溶解有机质的降解过程以及其耗氧情况还鲜有研究。本文基于2013年8月东海航次,对浮游植物(硅藻为主)死亡后释放的新鲜有机质进行人工受控培养,研究其降解过程及对DO的消耗,并评估该降解过程对低氧现象形成的贡献。研究发现:培养体系中溶解有机碳(dissolved organic carbon,DOC)和DO浓度皆随时间呈指数下降,总溶解态碳水化合物(total carbohydrate,TCHO)也出现明显降解;体系的初始DOC浓度越高,降解速率常数k(DOC)、k(DO)越大,k(DOC)受DOC浓度、活性以及DO浓度的影响;培养过程中细菌丰度明显增加,添加Hg Cl2的对比实验表明细菌在降解过程中起到重要作用。本文的研究结果表明,浮游植物死亡后释放的溶解有机质的快速降解及其对溶解氧的消耗,对长江口低氧环境的促成具有重要意义。
Dissolved organic matter(DOM) derived from marine phytoplankton is one of the main sources of DOM in the ocean. The biodegradation of fresh DOM released from dead phytoplankton can reduce significantly dissolved oxygen(DO) due to its high bioactivity and huge amount. At present, such a degradation process and the corresponding oxygen consumption are poorly studied. In this study, we sampled seawater in three stations by net collection in Changjiang River estuary, filtrated with 200 μm mesh and frozen at –20°C for at least 24 h. Samples were incubated to investigate the mechanism of degradation process and the consumption of dissolved oxygen, and possible link to hypoxia off the estuary. The results show that both dissolved organic carbon(DOC) and DO showed an exponential decay, during which total dissolved carbohydrate degraded significantly. Moreover, the degradation rate constant of DOC was influenced by the concentration and activity of DOC, so did the DO content. Bacteria density increased more apparently in our experiment without Hg Cl2 addition than with the adding, indicating the bacteria plays an important role in the degradation of DOM. Therefore, rapid degradation of DOM and the resulting consumption of oxygen would have an important impact on hypoxia off the Changjiang River estuary.
Dissolved organic matter(DOM) derived from marine phytoplankton is one of the main sources of DOM in the ocean. The biodegradation of fresh DOM released from dead phytoplankton can reduce significantly dissolved oxygen(DO) due to its high bioactivity and huge amount. At present, such a degradation process and the corresponding oxygen consumption are poorly studied. In this study, we sampled seawater in three stations by net collection in Changjiang River estuary, filtrated with 200 μm mesh and frozen at –20°C for at least 24 h. Samples were incubated to investigate the mechanism of degradation process and the consumption of dissolved oxygen, and possible link to hypoxia off the estuary. The results show that both dissolved organic carbon(DOC) and DO showed an exponential decay, during which total dissolved carbohydrate degraded significantly. Moreover, the degradation rate constant of DOC was influenced by the concentration and activity of DOC, so did the DO content. Bacteria density increased more apparently in our experiment without Hg Cl2 addition than with the adding, indicating the bacteria plays an important role in the degradation of DOM. Therefore, rapid degradation of DOM and the resulting consumption of oxygen would have an important impact on hypoxia off the Changjiang River estuary.
引文
王丹,孙军,周锋等,2009.2006年6月长江口低氧区及邻近水域浮游植物.海洋与湖沼,39(6):619-627
王亚,2011.长江河口水流输运时间的研究.上海:华东师范大学博士学位论文
朱卓毅,张经,吴莹等,2013.长江口外颗粒有机碳及光合色素在不同溶氧水平下早期降解速率研究.海洋与湖沼,44(1):1-8
刘诚刚,2012.中国近海浮游植物光合溶解有机碳生产研究.青岛:中国海洋大学博士学位论文
刘诚刚,宁修仁,郝锵等,2010.海洋浮游植物溶解有机碳释放研究进展.地球科学进展,25(2):123-132
刘海霞,李道季,高磊等,2012.长江口夏季低氧区形成及加剧的成因分析.海洋科学进展,30(2):186-197
孙军,2005.海洋中的凝集网与透明胞外聚合颗粒物.生态学报,25(5):1191-1198
叶属峰,黄秀清.2003.东海赤潮及其监视监测.海洋环境科学,22(2):10-14
赵冉,白洁,孙军等,2009.2006年夏季长江口及其邻近水域浮游植物群集.海洋湖沼通报,(2):88-96
赵其彪,孙军,李丹等,2015.东海低氧区及邻近水域浮游植物的季节变化.生态学报,35(7):2366-2379
郭术津,田伟,戴民汉等,2011.2009年夏季东海浮游植物群集.海洋科学进展,29(4):474-486
鲍红艳,2013.溶解态和颗粒态陆源有机质在典型河流和河口的来源、迁移和转化.上海:华东师范大学博士学位论文
潘洛安,2005.东海陆架及南海北部锋区微生物群落结构初探.上海:华东师范大学硕士学位论文
中华人民共和国国家标准海洋调查规范:第4部分:海水化学要素观测.2007.GB17378.4
Amon R M W,Fitznar H-P,Benner R,2001.Linkages among the bioreactivity,chemical composition,and diagenetic state of marine dissolved organic matter.Limnology and Oceanography,46(2):287-297
Azam F,Fenchel T,Field J G et al,1983.The ecological role of water-column microbes in the sea.Marine ecology progress series.Marine Ecology-Progress Series,10(3):257-263
Biddanda B,Benner R,1997.Carbon,nitrogen,and carbohydrate fluxes during the production of particulate and dissolved organic matter by marine phytoplankton.Limnology and Oceanography,42(3):506-518
Cherrier J,Bauer J E,Druffel E R M,1996.Utilization and turnover of labile dissolved organic matter by bacterial heterotrophs in eastern North Pacific surface waters.Marine Ecology Progress Series,139(1-3):267-279
Fuhrman J A,Azam F,1980.Bacterioplankton secondary production estimates for coastal waters of British Columbia,Antarctica,and California.Applied and Environmental Microbiology,39(6):1085-1095
Hedges J I,1992.Global biogeochemical cycles:progress and problems.Marine Chemistry,39(1-3):67-93
Hetland R D,Di Marco S F,2008.How does the character of oxygen demand control the structure of hypoxia on the Texas-Louisiana continental shelf?.Journal of Marine Systems,70(1-2):49-62
Hopkinson C S,Fry B,Nolin A L,1997.Stoichiometry of dissolved organic matter dynamics on the continental shelf of the northeastern U.S.A.Continental Shelf Research,17(5):473-489
Hung J-J,Chen C-H,Gong G-C et al,2003.Distributions,stoichiometric patterns and cross-shelf exports of dissolved organic matter in the East China Sea.Deep Sea Research Part II:Topical Studies in Oceanography,50(6-7):1127-1145
Kirchman D L,Suzuki Y,Garside C et al,1991.High turnover rates of dissolved organic carbon during a spring phytoplankton bloom.Nature,352(6336):612-614
Lee S,Fuhrman J A,1987.Relationships between biovolume and biomass of naturally derived marine bacterioplankton.Applied and Environmental Microbiology,53(6):1298-1303
Li D J,Zhang J,Huang D J et al,2002.Oxygen depletion off the Changjiang(Yangtze River)estuary.Science in China Series D:Earth Sciences,45(12):1137-1146
L?nborg C,Davidson K,álvarez-Salgado X A et al,2009.Bioavailability and bacterial degradation rates of dissolved organic matter in a temperate coastal area during an annual cycle.Marine Chemistry,113(3-4):219-226
Mannino A,Harvey H R,2000.Biochemical composition of particles and dissolved organic matter along an estuarine gradient:Sources and implications for DOM reactivity.Limnology and Oceanography,45(4):775-788
Meon B,Kirchman D L,2001.Dynamics and molecular composition of dissolved organic material during experimental phytoplankton blooms.Marine Chemistry,75(3):185-199
Myklestad S M,Sk?n?y E,Hestmann S,1997.A sensitive and rapid method for analysis of dissolved mono-and polysaccharides in seawater.Marine Chemistry,56(3-4):279-286
Passow U,1991.Species-specific sedimentation and sinking velocities of diatoms.Marine Biology,108(3):449-455
Sugimura Y,Suzuki Y,1988.A high-temperature catalytic oxidation method for the determination of non-volatile dissolved organic carbon in seawater by direct injection of a liquid sample.Marine Chemistry,24(2):105-131
Verdugo P,Alldredge A L,Azam F et al,2004.The oceanic gel phase:a bridge in the DOM-POM continuum.Marine Chemistry,92(1-4):67-85
Wang B D,2009.Hydromorphological mechanisms leading to hypoxia off the Changjiang estuary.Marine Environmental Research,67(1):53-58
Wei H,He Y C,Li Q J et al,2007.Summer hypoxia adjacent to the Changjiang Estuary.Journal of Marine Systems,67(3-4):292-303
Zhu Z Y,Zhang J,Wu Y et al,2011.Hypoxia off the Changjiang(Yangtze River)Estuary:oxygen depletion and organic matter decomposition.Marine Chemistry,125(1-4):108-116
王亚,2011.长江河口水流输运时间的研究.上海:华东师范大学博士学位论文
朱卓毅,张经,吴莹等,2013.长江口外颗粒有机碳及光合色素在不同溶氧水平下早期降解速率研究.海洋与湖沼,44(1):1-8
刘诚刚,2012.中国近海浮游植物光合溶解有机碳生产研究.青岛:中国海洋大学博士学位论文
刘诚刚,宁修仁,郝锵等,2010.海洋浮游植物溶解有机碳释放研究进展.地球科学进展,25(2):123-132
刘海霞,李道季,高磊等,2012.长江口夏季低氧区形成及加剧的成因分析.海洋科学进展,30(2):186-197
孙军,2005.海洋中的凝集网与透明胞外聚合颗粒物.生态学报,25(5):1191-1198
叶属峰,黄秀清.2003.东海赤潮及其监视监测.海洋环境科学,22(2):10-14
赵冉,白洁,孙军等,2009.2006年夏季长江口及其邻近水域浮游植物群集.海洋湖沼通报,(2):88-96
赵其彪,孙军,李丹等,2015.东海低氧区及邻近水域浮游植物的季节变化.生态学报,35(7):2366-2379
郭术津,田伟,戴民汉等,2011.2009年夏季东海浮游植物群集.海洋科学进展,29(4):474-486
鲍红艳,2013.溶解态和颗粒态陆源有机质在典型河流和河口的来源、迁移和转化.上海:华东师范大学博士学位论文
潘洛安,2005.东海陆架及南海北部锋区微生物群落结构初探.上海:华东师范大学硕士学位论文
中华人民共和国国家标准海洋调查规范:第4部分:海水化学要素观测.2007.GB17378.4
Amon R M W,Fitznar H-P,Benner R,2001.Linkages among the bioreactivity,chemical composition,and diagenetic state of marine dissolved organic matter.Limnology and Oceanography,46(2):287-297
Azam F,Fenchel T,Field J G et al,1983.The ecological role of water-column microbes in the sea.Marine ecology progress series.Marine Ecology-Progress Series,10(3):257-263
Biddanda B,Benner R,1997.Carbon,nitrogen,and carbohydrate fluxes during the production of particulate and dissolved organic matter by marine phytoplankton.Limnology and Oceanography,42(3):506-518
Cherrier J,Bauer J E,Druffel E R M,1996.Utilization and turnover of labile dissolved organic matter by bacterial heterotrophs in eastern North Pacific surface waters.Marine Ecology Progress Series,139(1-3):267-279
Fuhrman J A,Azam F,1980.Bacterioplankton secondary production estimates for coastal waters of British Columbia,Antarctica,and California.Applied and Environmental Microbiology,39(6):1085-1095
Hedges J I,1992.Global biogeochemical cycles:progress and problems.Marine Chemistry,39(1-3):67-93
Hetland R D,Di Marco S F,2008.How does the character of oxygen demand control the structure of hypoxia on the Texas-Louisiana continental shelf?.Journal of Marine Systems,70(1-2):49-62
Hopkinson C S,Fry B,Nolin A L,1997.Stoichiometry of dissolved organic matter dynamics on the continental shelf of the northeastern U.S.A.Continental Shelf Research,17(5):473-489
Hung J-J,Chen C-H,Gong G-C et al,2003.Distributions,stoichiometric patterns and cross-shelf exports of dissolved organic matter in the East China Sea.Deep Sea Research Part II:Topical Studies in Oceanography,50(6-7):1127-1145
Kirchman D L,Suzuki Y,Garside C et al,1991.High turnover rates of dissolved organic carbon during a spring phytoplankton bloom.Nature,352(6336):612-614
Lee S,Fuhrman J A,1987.Relationships between biovolume and biomass of naturally derived marine bacterioplankton.Applied and Environmental Microbiology,53(6):1298-1303
Li D J,Zhang J,Huang D J et al,2002.Oxygen depletion off the Changjiang(Yangtze River)estuary.Science in China Series D:Earth Sciences,45(12):1137-1146
L?nborg C,Davidson K,álvarez-Salgado X A et al,2009.Bioavailability and bacterial degradation rates of dissolved organic matter in a temperate coastal area during an annual cycle.Marine Chemistry,113(3-4):219-226
Mannino A,Harvey H R,2000.Biochemical composition of particles and dissolved organic matter along an estuarine gradient:Sources and implications for DOM reactivity.Limnology and Oceanography,45(4):775-788
Meon B,Kirchman D L,2001.Dynamics and molecular composition of dissolved organic material during experimental phytoplankton blooms.Marine Chemistry,75(3):185-199
Myklestad S M,Sk?n?y E,Hestmann S,1997.A sensitive and rapid method for analysis of dissolved mono-and polysaccharides in seawater.Marine Chemistry,56(3-4):279-286
Passow U,1991.Species-specific sedimentation and sinking velocities of diatoms.Marine Biology,108(3):449-455
Sugimura Y,Suzuki Y,1988.A high-temperature catalytic oxidation method for the determination of non-volatile dissolved organic carbon in seawater by direct injection of a liquid sample.Marine Chemistry,24(2):105-131
Verdugo P,Alldredge A L,Azam F et al,2004.The oceanic gel phase:a bridge in the DOM-POM continuum.Marine Chemistry,92(1-4):67-85
Wang B D,2009.Hydromorphological mechanisms leading to hypoxia off the Changjiang estuary.Marine Environmental Research,67(1):53-58
Wei H,He Y C,Li Q J et al,2007.Summer hypoxia adjacent to the Changjiang Estuary.Journal of Marine Systems,67(3-4):292-303
Zhu Z Y,Zhang J,Wu Y et al,2011.Hypoxia off the Changjiang(Yangtze River)Estuary:oxygen depletion and organic matter decomposition.Marine Chemistry,125(1-4):108-116