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1.
利用高精度多梯度热培养系统,对英国威尔士地区两类典型的北方泥炭沼泽中酚类物质和溶解有机碳释放的热敏感性进行了为期1年的调查研究.研究结果表明,雨养泥炭沼泽(Bog)酚类物质释放的热敏感性Q10(总酚)月变化为0.92～1.57,而矿养泥炭沼泽(Fen)的月变化范围为0.93～1.30.酚类释放的热敏感性与土壤温度大致呈正相关关系.此外,土壤温度与溶解有机碳释放的热敏感性Q10(DOC)也呈正相关关系.总体上,雨养泥炭沼泽的热敏感性比矿养泥炭沼泽略高.除温度外,水文条件和植被等多种环境因子对酚类物质和溶解有机碳释放的热敏感性也有较大影响.研究结果还表明酚碳热敏感性比值Q10o(总酚)/Q10(DOC)相对稳定,土壤温度的变化对其影响有限. 相似文献
2.
本研究通过测定有色溶解有机物(CDOM)的吸收光谱、荧光可溶性有机质(FDOM)的激发-发射-矩阵三维荧光光谱(excitation-emission-matrix spectra,EEMs)和稳定碳同位素组成(δ13C),系统探讨了长江口夏季水体可溶性有机质(DOM)的组成、来源、空间分布及河口混合行为等.研究结果表明,可溶性有机碳(DOC)浓度整体呈现由陆到海逐渐降低的趋势,表征有色溶解有机物含量水平的吸收系数a(355)与盐度呈负相关关系,指示可溶性有机质中荧光组分在河口的分布主要受稀释作用调控.利用EEMs并结合平行因子分析(PARAFAC)鉴定出代表陆源有机质的类腐殖质的荧光组分C2和C3,以及代表原地生产力的类蛋白质荧光组分C1和C4.由近岸到外海,表征海洋藻类生产力的C1组分在水体荧光有机质中所占比例增高,陆源信号则呈现逐渐降低趋势,与此相对应,外海水可溶性有机质具有高的光谱斜率S275–295/S350–400比值和重碳同位素组成.基于盐度vs.可溶性有机碳浓度、盐度vs.δ13C值的河流-海洋双端元混合模型,发现长江口最大混浊带存在可溶性有机碳的移除过程,且表现为以物理稀释作用为主的缺失性非保守混合行为.研究成果揭示了水动力条件是控制长江口-东海陆架系统可溶性有机质组成和空间分布的关键因素. 相似文献
3.
海洋浮游植物对磷的响应研究进展 总被引：3，自引：0，他引：3
磷是海洋浮游植物赖以生存的一种必需营养元素.海洋浮游植物对磷的响应,与初级生产力、碳循环以及固氮作用密切相关.总结了浮游植物可利用的磷源:优先吸收溶解无机磷;在寡磷海域,可通过相关酶类协助利用溶解有机磷来抵御无机磷的缺乏.对比了不同种类浮游植物对不同形态磷源利用方式的差异并从浮游植物生理学角度阐述了存在差异的根本原因.探讨了浮游植物对低磷环境的响应机制.近期的研究发现浮游植物细胞表面可以吸附磷,该发现有利于更加准确地衡量浮游植物承受的营养盐限制问题,进一步完善对海洋磷储库及其生物地球化学循环的认识.最后提出了今后需进一步研究的关键科学问题:浮游植物细胞表面吸附磷的机制;对不同结构有机磷化物的利用机理;浮游植物对磷的海洋生物地球化学循环的响应及反馈作用. 相似文献
4.
黄渤海有机碳的分布特征及收支评估研究 总被引：4，自引：1，他引：3
陆架边缘海是陆海相互作用研究中最为关键的区域,也是全球重要的碳储库,在区域物质循环过程中发挥着重要的作用。基于2012年5月和11月对黄渤海海域的综合调查,对该海域水体和沉积物中有机碳的含量与分布进行了分析,并结合相关文献资料对黄渤海有机碳的收支进行了估算。主要结论为:黄渤海溶解有机碳和颗粒有机碳均呈近岸河口区域高、离岸低的分布趋势;有机碳的组成以溶解有机碳为主,颗粒有机碳由海洋自生的有机碳和陆地来源的有机碳组成;黄渤海沉积物有机碳高值区主要分布在河口和泥质区,其组成也是由海洋自生和陆源混合而成,其中渤海以陆源为主,而黄海以海源为主。黄渤海有机碳收支评估表明,有机碳的主要来源为初级生产力产生的有机物,其贡献为(6 760±971)×104t/a,占有机碳输入总量的(74±10)%,沉积物再悬浮的通量为(884±200)×104t/a,东海向黄海输入的通量为(679±107)×104t/a,河流及陆源输入的通量为(643±63)×104t/a,大气干湿沉降的通量为(141±39)×104t/a,其贡献分别占有机碳输入总量的(10±2.2)%,(7.5±1.2)%,(7.0±0.7)%和(1.5±0.4)%;黄渤海有机碳的主要支出为呼吸消耗,其贡献为(5 190±746)×104t/a,占有机碳输出总量的(57±8.2)%,黄海向东海输出的通量为(2 150±370)×104t/a,有机碳沉积通量为(1 030±225)×104t/a,有机碳降解通量为(737±191)×104t/a,其贡献分别占有机碳输出总量的(24±4.1)%,(11±2.5)%和(8.0±2.1)%。有机碳收支评估表明黄渤海有机碳以海洋自生来源为主,且具有潜在碳的"汇"的特性,水体中外源输入和海洋自生有机碳的(1.6±0.3)%埋藏于该海域内。 相似文献
5.
6.
根据碳循环模式,通过无机碳和有机碳碳同位素记录,半定量-定量地计算了贵州新民剖面晚二叠世有机碳埋藏分数forg,同时结合表征古海洋初级生产力的疑源类、藻类与菌孢的丰度值,详细分析了有机碳埋藏分数forg、古海洋生产力与岩石中保存的残余TOC之间的耦合关系。该研究发现新民剖面晚二叠世初级生产力较有机碳埋藏分数forg对残余TOC的贡献更大。但这一结果仍需进一步论证:新民剖面和煤山剖面forg与δ13Ccarb的高度相关性暗示forg主要受控于δ13Ccarb,而在Kump碳循环模型中忽略了晚二叠世火山活动对无机碳同位素组成的重要影响。 相似文献
7.
惰性有机碳(RDOC, Recalcitrant Dissolved Organic Carbon)作为难以被生物降解的有机碳, 可以在水体中保存数千年, 构成长期碳储。岩溶区浮游植物利用岩溶水中丰富的HCO– 3进行光合作用, 为异养细菌生长提供充足的有机质底物, 促进异养细菌代谢, 形成RDOC。本文以广西柳江为例, 通过δ14C示踪法、荧光实时定量PCR法、原位微生物法对流域内细菌基因丰度、RDOC浓度等进行培养和测试, 结合环境因子对流域内RDOC的变化趋势进行分析讨论。研究区RDOC浓度介于1.46~2.66 mg·L–1之间, 平均1.85 mg·L–1, 占DOC的48.16%~92.61%, 平均占65.83%, 表现出明显的时空变化特征: 平水期水温升高、水体浊度降低, 浮游生物初级生产力增加, 产生较多内源有机碳, 为异养细菌提供充足的有机质底物, 细菌丰度和初级生产力增加, RDOC浓度明显高于丰水期, 主要受流域内异养细菌生物效应影响; RDOC浓度在水库坝后明显减小, 该采样点较缓的流速使有机质和生物聚合物更易沉降, 进而留存在水体中的DOC及RDOC减少, 主要受水动力条件控制。研究结果表明流域内RDOC受生物效应和水体理化性质共同影响, 异养细菌是流域内RDOC的主要贡献者, 同时浮游生物产生的内源有机碳对RDOC形成有促进作用。 相似文献
8.
增江颗粒有机碳同位素的AMS研究初报 总被引：3，自引：0，他引：3
全球河流每年向海洋输送约1Gt(1015g)的碳,其中40%为有机碳。然而,在海洋沉积物中却难以寻找到足量的陆地碳的生物地球化学标记[1]。显然,陆地碳在河流搬运过程中经历了复杂的生物地球化学变化,乃至“踪迹全无”。河流有机碳可大体上划分为颗粒态(POC)和溶解态(DOC)两种基本类型。就全球范围讲,河流输送的POC和DOC在数量上相当或DOC略高些。但在一些高浑浊的河流,尤其是亚洲季风区的河流中,POC在有机碳中却占绝对优势。如珠江干流水体中POCDOC比值高达5.0左右[2]。因此,亚洲季风区河流中所搬运的POC对其注入水域的生物地球化学过程影响深远。河流有机质的来源复 相似文献
9.
《地球科学进展》2016,(7)
海洋碳汇对气候变化的响应与反馈是一个系统的科学命题,也是当前国际地球系统科学领域的前沿热点问题,需要通过微观与宏观结合、古今链接、多学科交叉融合进行深入研究。在我国科学家发起的海洋生物地球化学"戈登科学前沿论坛"(Gordon Research Conferences,GRC)首届论坛上,以海洋生物泵(Biological Pump,BP)、微型生物碳泵(Microbial Carbon Pump,MCP)以及碳酸盐泵(Carbonate Counter Pump,CCP)等海洋储碳机制为核心,深入研讨了海洋碳汇的过程与效应,起到了引领国际海洋学科发展方向的作用。国内学界也积极行动起来,在第四届地球系统科学大会上组织了海洋碳汇专题,从古海洋碳汇、现代海洋碳循环及海洋碳汇的生物海洋学过程3个方面开展研讨。海洋微型生物生态学过程与海洋碳汇以海洋浮游植物、细菌、古菌、病毒以及不同微型生物间的互作为切入点,探讨了微型生物的储碳和固碳作用的过程及其与全球气候变化的关系。古海洋碳汇方向的报告在时间尺度上跨越了从18~8亿年前的中元古代到距今2.5 Ma的第四纪,涵盖了包括古海洋碳汇形成的古海洋环境、古海洋碳汇的生态环境效应等前沿科学问题;古海洋碳汇的报告为现代海洋碳汇研究提供了有益的借鉴,并有助于本领域科学家对海洋碳汇的历史演化观的认识。现代海洋碳循环过程方面,专题报告结合时间梯度和空间梯度,以南海珊瑚礁碳循环源汇争议为代表,探讨了碳循环中的初级生产力、溶解有机碳的来源与有机碳的降解等过程,对现代海区和全球变化背景下海洋的源汇评估提出了新的想法与研究方向。 相似文献
10.
11.
Neil S. Shifrin 《Estuaries and Coasts》1980,3(3):230-233
The effects of applied filtration vacuum and incubation time on the release of dissolved organic carbon (DOC) by natural phytoplankton populations dominated by diatoms were examined. The rate of primary production and release of DOC remained reasonably constant during a 5 hour incubation period. The measured release of DOC was found to be quite sensitive to the applied filtration vacuum, ranging from near 2 percent of fixed carbon (neglecting respiration) for gravity-filtered samples to 36 percent for samples filtered at 40 cm Hg vacuum. 相似文献
12.
DOC dynamics in a small temperate estuary: Simultaneous addition and removal processes and implications on observed nonconservative behavior 总被引：2，自引：0，他引：2
Dissolved organic carbon (DOC) dynamics in the Pawcatuck River estuary, a small temperate estuary in Rhode Island, United
States, were examined through the use of field transect and in situ production studies. In late summer, when river discharge
was minimal, phytoplankton blooms occurred in the upper reaches of the estuary and released large amounts of autochthonous
DOC that accumulated in the middle reaches of the estuary. DOC production rates in August months, calculated both by mixing
diagrams and in situ DOC incubations, ranged from 6.67 to 34.7 μmol C l−1 d−1 and were positively correlated with DCMU-enhanced fluorescence, an estimate of phytoplankton photosynthetic activity (r2=0.796, p<0.001). The percent extracellular release (PER) of DOC from phytoplankton, calculated from measured in situ DOC
production and net phytoplankton production (NPP) rates, ranged from 5.8% to 40.6% and was negatively correlated with NPP
(r2=0.80, p<0.01). Accumulated DOC was principally nonhumic in nature, and the humic DOC component behaved quite differently
with either conservative mixing or significant removal at the head of the estuary. Humic removal at times amounted to approximately
50% of the humic material and 25% of the total incoming riverine DOC. These large humic losses were not observed in bulk DOC-salinity
mixing diagrams but required distinct analyses of the humic and nonhumic components. DOC addition and removal processes co-occur
in this system and observation of bulk DOC mixing diagrams may mask the true dynamic nature of the estuarine DOC pool. The
net result of the DOC addition and removal processes is a seasonally variable transformation of a humic-rich incoming riverine
DOC to a nonhumic enriched bulk DOC component that varies seasonally and with river discharge. 相似文献
13.
Peter H. Doering Candace A. Oviatt James H. McKenna Laura W. Reed 《Estuaries and Coasts》1994,17(3):521-536
The distributions of dissolved organic carbon (DOC), phytoplankton biomass (as measured by in vivo fluorescence), total nitrogen and phosphorus, and light extinction were observed on 10 cruises during 1989 and 1990 in the Pawcatuck River estuary located in southern Rhode Island. In the lower estuary, the distance of peak phytoplankton biomass from the head of the estuary was positively correlated with river discharge while the magnitude of the peak increased with decreasing discharge. High light-extinction appeared to limit the accumulation of biomass in the upper estuary. Variability in light extinction was largely (50%) explained by variation in the concentration of DOC. Salinity versus constituent plots suggested that DOC behaved nonconservatively in the estuary. These observational data indicate that the mixing behavior of DOC in the estuary influences light extinction and thus may limit accumulation of phytoplankton biomass in the upper estuary. This interpretation of observational data was supported by experimental work that demonstrated the significant contribution of DOC to light extinction, and by measurements, of phytoplankton productivity that showed greater light limitation in the upper estuary. 相似文献
14.
Bruce Peterson Brian Fry Meredith Hullar Susan Saupe Richard Wright 《Estuaries and Coasts》1994,17(1):111-121
The distributions of dissolved organic carbon (DOC) and the natural carbon isotope ratio of DOC (DO13C) in estuaries reflect the predominant sources and sinks of organic matter from both allochthonous and autochthonous origins. The traditional view is that DOC in land-margin ecosystems reflects mainly the mixing of land-derived and oceanic DOC. However, this view is not consistent with the bulk of our data from a survey of DOC and DO13C distributions in estuaries on the East and Gulf coasts of the USA. While it is accurate that the DOC in estuaries includes material derived from land and from the ocean, the distributions of DOC and DO13C in several estuaries reflect additional DOC inputs from estuarine phytoplankton and tidal marshes. Even when DOC concentrations were distributed conservatively, the isotopic composition of the DOC revealed the existence of a dynamic cycle of DOC input and removal in some systems. 相似文献
15.
基于2004年夏季水华暴发期和冬季在梅梁湾及大太湖各2次采样,分析了夏季、冬季CDOM的特征及其可能的来源,发现夏季CDOM吸收系数、叶绿素a浓度均明显高于冬季,DOC浓度、CDOM吸收系数a(355)的变化范围分别为5.17～12.42 mg/L、2.57～6.77 m-1,最大值均出现在冬季(12月15日)的直湖港入湖口.CDOM吸收系数与DOC浓度、定标后的荧光值一般都存在显著正相关,但夏季由于受浮游植物降解的影响,与DOC浓度和荧光的相关性明显低于冬季.表征CDOM组成和来源的参数比吸收系数、M值、S值存在显著的季节差异,夏季吸收系数a*(355)值明显要大于冬季,而S值、M值则要小于冬季.夏季水华暴发时CDOM吸收系数与叶绿素a浓度空间分布较为一致,吸收系数与叶绿素a浓度存在正相关,浮游植物降解产物可能是水体中CDOM的重要来源;相反,冬季CDOM吸收系数呈现从梁溪河入湖口、湾内往湾口递减的趋势,其来源可能主要以陆源为主,受入湖河流的影响较大. 相似文献
16.
We measured dissolved and particulate organic carbon (DOC and POC) in samples collected along 13 transects of the salinity gradient of Chesapeake Bay. Riverine DOC and POC end-members averaged 232±19 μM and 151±53 μM, respectively, and coastal DOC and POC end-members averaged 172±19 μM and 43±6 μM, respectively. Within the chlorophyll maximum, POC accumulated to concentrations 50–150 μM above those expected from conservative mixing and it was significantly correlated with chlorophylla, indicating phytoplankton origin. POC accumulated primarily in bottom waters in spring, and primarily in surface waters in summer. Net DOC accumulation (60–120 μM) was observed within and downstream of the chlorophyll maximum, primarily during spring and summer in both surface and bottom waters, and it also appeared to be derived from phytoplankton. In the turbidity maximum, there were also net decreases in chlorophylla (?3 μg l?1 to ?22 μg l?1) and POC concentrations (?2 μM to ?89 μM) and transient DOC increases (9–88 μM), primarily in summer. These occurred as freshwater plankton blooms mixed with turbid, low salinity seawater, and we attribute the observed POC and DOC changes to lysis and sedimentation of freshwater plankton. DOC accumulation in both regions of Chesapeake Bay was estimated to be greater than atmospheric or terrestrial organic carbon inputs and was equivalent to ≈10% of estuarine primary production. 相似文献
17.
Britta Planer-Friedrich Cornelia Härtig Heidi Lissner Jörg Steinborn Elke Süß M. Qumrul Hassan Anwar Zahid Mahmood Alam Broder Merkel 《Applied Geochemistry》2012
Currently, the most widely accepted hypothesis to explain high As concentrations in Bangladesh groundwaters is that dissolved organic C (DOC) reduces solid Fe (hydr)oxides and mobilizes sorbed arsenate. The nature of the DOC and its release mechanism are still controversial. Based on weekly to biweekly sampling over the course of one monsoon cycle at six monitoring wells of different depths, it is proposed that storativity changes drive natural DOC release from clay–peat layers to the adjacent aquifers. With a decrease in hydraulic heads during the dry season, total mineralization and DOC concentrations increased. With the onset of the rainy season and an increase in hydraulic heads, release of clay–peat derived components stopped and vertical water displacement due to groundwater recharge from rainwater occurred, causing aquifer flushing and a decrease in total mineralization and DOC concentrations. Total As and DOC concentrations correlated over depth. However, at the depth of maximum concentrations, the As peak was observed during the rainy season. At present, the reason for this inverse seasonal trend between As and DOC is unclear. Higher mineralization or DOC concentrations could lead to increased As sorption or the increased arsenite release is a time-lag abiotic or microbial response to the DOC peak. The vulnerability of the Pleistocene aquifer towards increased As concentrations was found to be much higher than previously assumed. Though sorption capacities were determined to be higher than in the Holocene aquifer, probably due to intact Fe (hydr)oxides, long-term continuous As input from overlying clay and peat layers by the proposed seasonal storativity changes has led to increased aqueous As concentrations of 85 μg/L, considerably higher than drinking water standards. Until now, aquifer and especially aquitard and aquiclude hydraulics have not been considered sufficiently when attempting to explain As mobilization in Bangladesh. 相似文献
18.
Quantifying living roots in a marsh is a necessary but difficult task in wetland research. The two main difficulties usually encountered are distinguishing living from dead roots and processing a dense mat of fine roots. We found that living roots of salt-marsh plants release much more dissolved organic carbon (DOC) in boiling water than dead roots. Based on the finding, we developed a DOC procedure to quantify living roots of Spartina alterniflora and Juncus roemerianus. The DOC released in boiling water is a function of root activity, and the amount released can be used to calculate the living root biomass of a sample. The amount of living roots determined by the DOC method correlated well with the amount of living roots determined by the manual, sorting method (r2 = 0.78, p<0.01). The DOC method is more objective, precise, and much less tedious than the manual sorting method. 相似文献
19.
Farooq Azam Grieg F. Steward David C. Smith Hugh W. Ducklow 《Journal of Earth System Science》1994,103(2):341-351
In the Arabian Sea, temporal contiguity of highly oligotrophic and eutrophic periods, along with high water temperatures,
may result in unique features of bacteriaorganic matter coupling, nutrient cycling and sedimentation, which are unlike those
in the classical oligotrophic and eutrophic waters. Bacteria-phytoplankton interactions are suggested to influence phytoplankton
aggregation and its timing. It is also hypothesized that, within aggregates, hydrolytic ectoenzyme activity, together with
condensation reactions between the hydrolysis products, produce molecular species which are not readily degraded by pelagic
bacteria. Accumulation of a reservoir of such slow-to-degrade dissolved organic carbon (DOC) is proposed to be a carbon flux
and energy buffer, which moderates the response of bacteria to the dramatic variations in primary production in the Arabian
Sea. Use of the slow-to-degrade DOC pool during the intermonsoon could temporarily render the Arabian Sea net-heterotrophic
and a source of CO2 to the atmosphere. Stored DOC is also suggested to balance the observed deficit between mesopelagic carbon demand and the
sinking particulate organic carbon supply. Knowledge of the significance of bacteria in carbon storage and cycling in the
Arabian Sea is needed to understand the response of the ocean’s biogeochemical state to strong physical forcing and climate
change. 相似文献
20.
Patrick R. Hutchins Erik M. Smith Eric T. Koepfler Richard F. Viso Richard N. Peterson 《Estuaries and Coasts》2014,37(3):736-750
Groundwater discharge is increasingly recognized as a significant source of nutrient input to coastal waters, relative to surface water inputs. There remains limited information, however, on the extent to which nutrients and organic matter from each of these two flowpaths influence the functional responses of coastal microbial communities. As such, this study determined dissolved organic carbon (DOC) and nutrient concentrations of surface water runoff and groundwater from both an urbanized and a relatively pristine forested drainage basin near Myrtle Beach, South Carolina, and quantified the changes in production rates and biomass of phytoplankton and bacterioplankton in response to these inputs during two microcosm incubation experiments (August and October, 2011). Rainwater in the urbanized basin that would otherwise enter the groundwater appeared to be largely rerouted into the surface flowpath by impervious surfaces, bypassing ecosystem buffers and filtration mechanisms. Surface runoff from the developed basin was most enriched in nutrients and DOC and yielded the highest production rates of the various source waters upon addition to coastal waters. The metabolic responses of phytoplankton and bacterioplankton were generally well predicted as a function of initial chemical composition of the various source waters, though more so with bacterial production. Primary and bacterial productivities often correlated at reciprocal time points (24-h measurement of one with the 72-h measurement of the other). These results suggest human modification of coastal watersheds enhances the magnitude of dissolved constituents delivered to coastal waters as well as alters their distributions between surface and groundwater flowpaths, with significant implications for microbial community structure and function in coastal receiving waters. 相似文献