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1.
Time series of chromophoric dissolved organic matter (CDOM) light absorption coefficients indicate a local origin for a large fraction of the CDOM in the upper water column of the Sargasso Sea. In the present study, we demonstrate that CDOM is produced in bacterial culture experiments using Sargasso Sea water and naturally occurring microbial assemblages. Seawater cultures were prepared and grown at in situ temperatures in the dark for periods of weeks. Selected cultures were treated with amendments including inorganic nutrients, glucose, phytoplankton exudates, and zooplankton excretia. In all experiments, when bacterial biomass increased, CDOM increased during the first week of the experiment, followed by a decrease over a longer period of time. Cultures amended with both glucose and inorganic nitrogen and phosphorus produced more CDOM than controls or cultures amended with glucose or inorganic nutrients alone. However, when complex DOM substrates (derived from phytoplankton or zooplankton cultures) were added to seawater cultures, there was a net accumulation of CDOM over the course of the experiments. These data suggest that, in addition to microbial growth, the quality of the substrate plays an important role in net CDOM production. ‘New’ CDOM produced in culture was spectroscopically similar to CDOM appearing below the surface during summer stratification. The results of the present study support a new paradigm for CDOM in the open ocean, which allows for local origin and significant dynamics. Appreciation of CDOM dynamics will, in turn, add to our understanding of microbial productivity, photochemical rate processes, and ultraviolet radiation availability in the global ocean. 相似文献
2.
David J. Carlson Lawrence M. Mayer Mary Louise Brann Timothy H. Mague 《Marine Chemistry》1985,16(2):141-153
Several monomeric organic compounds, including amino acids, sugars, and fatty acids, were found to bind abiologically to dissolved macromolecular materials in particle-free seawater at natural substrate concentrations. The binding primarily occurred in ocean surface waters, at rates slower than in situ biological utilization rates of most of the compounds. Seasonal patterns of binding in Gulf of Maine waters may have been related to seasonal variations in macroalgal exudation of polyphenolic materials. Enhanced reactivity of relatively hydrophobic monomers implicated hydrophobic effects as potentially important in marine organic condensations. The resultant condensates showed high particle reactivity, consistent with low concentrations of dissolved condensed materials in seawater. 相似文献
3.
The dissolved organic matter in seawater is grouped into two fractions which are defined as having greatly differing reactivities with respect to both chemical and biological decomposition. One fraction, which constitutes the bulk of the material, is extremely stable and inert and is only slowly degraded by either chemical or biological processes. The other fraction, which is composed of trace organic compounds derived from living organisms, contains components such as free amino acids which are rapidly degraded, probably by marine organisms which use these compounds as a food source. Conclusions about the cycle of organic compounds in seawater based on total organic carbon concentrations could thus be misleading, since pathways involving labile trace organic constituents would be completely obscured. Investigations of the distribution, concentration, and possible diagenetic reactions of specific organic compounds are necessary in order to elucidate the cycle of these compounds in the oceans. 相似文献
4.
海水中的一氧化碳(CO)主要由溶解有色有机物(CDOM)光降解产生,且CO的光致生成量受到环境因素的影响。采集了胶州湾及其河口表层水样,通过实验室模拟实验开展了不同的环境条件(辐射强度、光照时间、温度、pH和盐度)以及水体中CDOM的来源对CO光致生成的影响研究。结果表明胶州湾海水中CO的光致生成速率随辐射强度的增强、水温的升高和水体pH的增大而增大;随着光照时间的延长、水体盐度的增大而逐渐减小;不同来源的CDOM对水体中CO的光致生成速率产生了不同的影响。 相似文献
5.
胶州湾海水中一氧化碳光致生成影响因素的研究 总被引：3，自引：1，他引：2
海水中的一氧化碳(CO)主要由溶解有色有机物(CDOM)光降解产生,且CO的光致生成量受到环境因素的影响。采集了胶州湾及其河口表层水样,通过实验室模拟实验开展了不同的环境条件(辐射强度、光照时间、温度、pH和盐度)以及水体中CDOM的来源对CO光致生成的影响研究。结果表明胶州湾海水中CO的光致生成速率随辐射强度的增强、水温的升高和水体pH的增大而增大;随着光照时间的延长、水体盐度的增大而逐渐减小;不同来源的CDOM对水体中CO的光致生成速率产生了不同的影响。 相似文献
6.
Release of dissolved organic matter during oxic and anoxic decomposition of salt marsh cordgrass 总被引：1，自引：0，他引：1
Xu-Chen Wang Liannea Litz Robert F. Chen Wei Huang Peng Feng Mark A. Altabet 《Marine Chemistry》2007,105(3-4):309-321
Chromophoric dissolved organic matter (CDOM), as the light absorbing fraction of bulk dissolved organic matter (DOM), plays a number of important roles in the global and local biogeochemical cycling of dissolved organic carbon (DOC) and in controlling the optical properties of estuarine and coastal waters. Intertidal areas such as salt marshes can contribute significant amounts of the CDOM that is exported to the ocean, but the processes controlling this CDOM source are not well understood. In this study, we investigate the production of DOM and CDOM from the decomposition of two salt marsh cordgrasses, Spartina patens, a C4 grass, and Typha latifolia, a C3 grass, in well-controlled laboratory experiments. During the seven-week incubation period of the salt marsh grasses in oxic and anoxic seawater, changes in dissolved organic carbon (DOC) concentrations, dissolved nitrogen (DN) concentrations, stable carbon isotopic composition of DOC (DOC-δ13C), and CDOM fluorescence demonstrate a significant contribution of DOC and CDOM to estuarine waters from salt marsh plants, such as Spartina and Typha species. In the natural environment, however, the release processes of CDOM from different cordgrass species could be controlled largely by the in situ oxic and anoxic conditions present during degradation which affects both the production and decomposition of DOC and CDOM, as well as the optical properties of CDOM in estuarine and coastal waters. 相似文献
7.
水体中有色可溶性有机物的研究进展 总被引：12，自引：0，他引：12
有色可溶性有机物(CDOM)是水体中一类重要的光吸收物质,在短波的吸收大大降低了紫外辐射在水体的衰减,因而其光学行为和生物地球化学循环将对水体生态系统产生重要影响。CDOM在水体生态系统、水色遥感和全球碳循环研究中具有广阔的应用前景。文章综述了国内外CDOM研究现状与动态,其中包括CDOM的光吸收特性、荧光特性、光化学降解以及CDOM和DOC浓度的水色遥感,最后提出在内陆水体湖泊中开展CDOM研究的设想。 相似文献
8.
自2007年以来,浒苔绿潮已经连续15年在南黄海暴发。浒苔（Ulva prolifera）作为主要肇事藻种,在暴发过程中向海水释放大量的溶解有机碳（DOC）。然而,这些藻源DOC能否长期保存在海洋中,主要取决于它们的生物可利用性,目前关于此方面的研究甚少。本研究在浒苔绿潮大规模暴发时期（2019年6月）,分别在浒苔暴发海区和无浒苔海区各选择3个站位富集表层海水,在实验室进行长期（300 d）的DOC降解实验。结果发现,在60 d内,不同站位富集海水中的DOC浓度随着微生物的利用快速下降,微生物丰度也在第60天达到峰值,表明这些被消耗的DOC是生物可利用性高的活性DOC（LDOC）。60 d后,剩余的DOC可抵抗微生物的降解,在60~300 d内保持稳定,表明这些DOC是具有强稳定性的惰性DOC（RDOC）。最终发现,浒苔暴发海水的RDOC占富集DOC的46%,明显高于无浒苔海水的（36%）。并且,荧光溶解有机物（FDOM）中活性的类蛋白组分随着微生物的利用被快速消耗,惰性的类腐殖质组分逐渐积累,暗示了在降解过程中LDOC逐渐向RDOC转化。可见,浒苔绿潮暴发除了在短时间内增加海水中的DOC浓度,在长时间尺度上也可增加近海RDOC库的积累。 相似文献
9.
Variation of dissolved organic matter and fluorescence characteristics before,during and after phytoplankton bloom 总被引：3，自引：0，他引：3
Marut Suksomjit Seiya Nagao Kazuhiko Ichimi Tatsuo Yamada Kuninao Tada 《Journal of Oceanography》2009,65(6):835-846
The variation of dissolved organic matter (DOM) and fluorescence characteristics during the phytoplankton bloom were investigated
in Yashima Bay, at the eastern part of the Seto Inland Sea, Japan. We found significant accumulations of dissolved organic
carbon (DOC), dissolved organic nitrogen (DON), chromophoric dissolved organic matter (CDOM) fluorescence, and UV260 during the phytoplankton bloom period in 2005, although lower accumulations of DOC and DON and only increases of CDOM fluorescence
were observed during the bloom period in 2006. Little or no correlation between DOM and phytoplankton abundance might be due
to the composition of DOM, which is a complex mixture of organic materials. The 3D-EEM results revealed that the DOM produced
around the phytoplankton bloom period contained tyrosine, tryptophan, and humic-like substances. Our results showed that the
occurrence of phytoplankton bloom contributed to the production of DOM in coastal water but the DOM accumulation depended
on the type of phytoplankton bloom, the phytoplankton species in particular. From our results, we concluded that phytoplankton
have a great role in the dynamics of DOM as a producer in a coastal environment. 相似文献
10.
LIU Qiong PAN Delu BAI Yan WU Kai CHEN Chen-Tung Arthur SUN Jun ZHANG Lin 《海洋学报(英文版)》2013,32(2):1-11
The retrieval of dissolved organic carbon (DOC) distribution by remote sensing is mainly based on the empirical relationship of DOC concentration and colored dissolved organic matter (CDOM) concentration in many literatures. To investigate the nature of this relationship, the distributions and mixing behaviors of DOC and CDOM are reviewed in the world’s major estuaries and bays. It is found that, generally, the CDOM concentration is well correlated with the salinity in most estuaries, while DOC usually shows a nonconservative behavior which leads to a weak correlation between the DOC concentration and the CDOM concentration. To establish a good satellite reversion of the DOC concentration, the East China Sea(ECS) was taken as an example, and the mixing behavior of DOC and CDOM as well as the influence of biogeochemical processes were analyzed except for the physical mixing process with the data from late autumn (November, 2010) and winter (December, 2009) cruises. In the two ECS cruises, the CDOM concentration was found to be tightly correlated with the salinity, influenced little by the photochemical or biological processes. The data from the winter cruise show that DOC followed a conservative mixing along the salinity gradient, while in the late autumn cruise it was significantly affected by the biological activities, resulting in a poor correlation between the DOC and the CDOM. Accordingly, an improved DOC algorithm (CSDM) was proposed: when the biological influence was significant (Chl a greater than 0.8 μg/dm3 ), DOC was retrieved by the conservative and biological model, and if the conservative mixing was dominant (Chl a less than 0.8 μg/dm3 ), the direct DOC concentration and CDOM concentration relationship was used. Based on the proposed algorithm, a reasonable DOC distribution for the ECS from satellite was obtained in this study, and the proposed method can be applied to the other large river-dominant marginal sea. 相似文献
11.
水体中的有色可溶性有机物(又称"黄色物质")是遥感监测水质分类的主要参数之一,研究其光谱吸收性质具有重要的实际意义。东海海区受长江冲淡水等陆源输入的影响,水体浑浊,光学性质复杂,以往对该区域CDOM吸收特征的研究相对较少。利用"九○八"我国近海海洋光学调查航次数据,获得了2006-2007年四个季节东海水体样品CDOM的光谱吸收数据,建立了包括杭州湾高浑浊水体、长江冲淡水、外海水体等东海不同水体类型的CDOM光谱模型及其典型波段的吸收系数分布情况。发现近岸受陆源输入影响大的海区其光谱性质与外海有明显区别,主要体现为近岸尤其在杭州湾附近站点短波段吸收系数值非常高,而且随波长增加吸收系数曲线衰减迅速,同时还有一定的季节变化,外海站点短波段吸收值则明显要低。这反映了CDOM的陆源输入特性,愈向外受到海水的混合稀释作用愈显著,验证了CDOM可以作为近岸海水水质监测的重要参数。对该海区内CDOM的实测荧光性质进行了相关分析,结果表明CDOM荧光与吸收系数之间有很好的线性相关关系,可以作为荧光方法遥感监测该海区CDOM的有价值的参考。 相似文献
12.
Amino acids, neutral sugars and amino sugars were analyzed to investigate the chemical composition and diagenetic processing of suspended particulate organic matter (POM, > 100 nm), high-molecular-weight dissolved organic matter (HMW DOM, 1–100 nm) and low-molecular-weight dissolved organic matter (LMW DOM, < 1 nm) at the time-series stations near Bermuda (BATS) and Hawaii (HOT). Differences between BATS and HOT were principally related to location-specific biogeochemical processes and water mass ventilation ages. Concentrations of amino acids, neutral sugar and amino sugars in unfiltered seawater sharply declined with depth at both stations, indicating an upper ocean source and rapid turnover of these components. The size distribution of organic matter was heavily skewed to smaller molecular sizes. Depth comparisons showed that larger size classes of organic matter were more efficiently removed than smaller size classes. Carbon-normalized yields of amino acids, neutral sugars and amino sugars decreased rapidly with depth and molecular size. Together these biochemicals accounted for 55% of organic carbon in surface POM but only 2% of the organic carbon in LMW DOM in deep water. Chemical compositions showed distinct differences between organic matter size classes indicating the extent of diagenetic processing increased with decreasing molecular size. These findings are consistent with the size-reactivity continuum model for organic matter in which bioreactivity decreases with decreasing molecular size and diagenetic processes lead to the formation of smaller components that are resistant to biodegradation. The data also provided evidence for a size-composition continuum. Carbon-normalized yields of amino acids, neutral sugars and amino sugars were sensitive indicators of diagenetic alterations. Diagenetic indicators based on amino acid compositions revealed distinct patterns for the North Pacific and Sargasso Sea possibly indicating the influence of varying sources or diagenetic processing. 相似文献
13.
Seasonal dynamics in colored dissolved organic matter in the Mediterranean Sea: Patterns and drivers
Two autonomous profiling “Bio-Argo” floats were deployed in the northwestern and eastern sub-basins of the Mediterranean Sea in 2008. They recorded at high vertical (1 m) and temporal (5 day) resolution, the vertical distribution and seasonal variation of colored dissolved organic matter (CDOM), as well as of chlorophyll-a concentration and hydrological variables. The CDOM standing stock presented a clear seasonal dynamics with the progressive summer formation and winter destruction of subsurface CDOM maxima (YSM, for Yellow Substance Maximum). It was argued that subsurface CDOM is a by-product of phytoplankton, based on two main characteristics, (1) the YSM was located at the same depth than the deep chlorophyll maximum (DCM) and (2) the CDOM increased in summer parallels the decline in chlorophyll-a. These observations suggested an indirect but tight coupling between subsurface CDOM and phytoplankton via microbial activity or planktonic foodweb interactions. Moreover, the surface CDOM variations observed both by floats and MODIS displayed different seasonal dynamics from what recorded at subsurface one. This implies that CDOM standing stock can be hardly detected by satellite. It is worthnoting that surface CDOM was found to be more related to the sea surface temperature (SST) than chlorophyll-a concentration, suggesting its physical origin, in contrast to the biological origin of YSM and subsurface standing stocks. 相似文献
14.
High-resolution measurements of chromophoric dissolved organic matter in the Mississippi and Atchafalaya River plume regions 总被引：4，自引：0，他引：4
Chromophoric dissolved organic matter (CDOM) was measured in the spring and summer in the northern Gulf of Mexico with the ECOShuttle, a towed, instrumented, undulating vehicle. A submersible pump mounted on the vehicle supplied continuously flowing, uncontaminated seawater to online instruments in the shipboard laboratory and allowed discrete samples to be taken for further analysis. CDOM in the northern Gulf of Mexico was dominated by freshwater inputs from the Mississippi River through the Birdfoot region and to the west by discharge from the Atchafalaya River. CDOM was more extensively dispersed in the high-flow period in the spring but in both time periods was limited by stratification to the upper 12 m or so. Thin, subsurface CDOM maxima were observed below the plume during the highly stratified summer period but were absent in the spring. However, there was evidence of significant in situ biological production of CDOM in both seasons.The Mississippi River freshwater end member was similar in spring and summer, while the Atchafalaya end member was significantly higher in the spring. In both time periods, the Atchafalaya was significantly higher in CDOM and dissolved organic carbon (DOC) than the Mississippi presumably due to local production and exchange within the coastal wetlands along the lower Atchafalaya which are absent along the lower Mississippi. Nearshore waters may also have higher CDOM due to outwelling from coastal wetlands. High-resolution measurements allow the differentiation of various water masses and are indicative of rapidly varying (days to weeks) source waters. Highly dynamic but conservative mixing between various freshwater and marine end members apparently dominates CDOM distributions in the area with significant in situ biological inputs (bacterial degradation of phytoplankton detritus), evidence of flocculation, and minor photobleaching effects also observed. It is clear that high-resolution measurements and adaptive sampling strategies allow a more detailed examination of the processes that control CDOM distributions in river-dominated systems. 相似文献
15.
依据2017年8—9月对黄海海域溶解有机物(DOM)的调查，探讨了夏季黄海海水中溶解有机碳(DOC)和有色溶解有机物(CDOM)的空间分布特征。在表层海水中，受陆源影响较大的近岸海域CDOM含量相对较高，北黄海冷水团区域由于水产养殖的饵料引起DOC浓度升高，且该部分DOC以无色为主。DOC浓度随深度逐渐降低，而CDOM逐渐升高，该特征在冷水团区域更为显著，因此DOC和CDOM在冷水团区域的表底差异远大于浅水区的非冷水团区域。陆源输入和初级生产是引起表层DOC升高的主要原因，而光漂白则引起CDOM降低，同时光漂白还导致表层水体中CDOM分子量和芳香性低于底层。底层溶解氧饱和度在冷水团为80%～93%，均表现为弱不饱和状态。层化不仅阻碍了O2向底层水体输送，还抑制了DOC和CDOM的垂向混合，这是引起冷水团区域表底层DOC和CDOM差异较大的主要原因。 相似文献
16.
西太平洋冬季上层水体有色溶解有机物的分布和转化特征 总被引：3，自引：1，他引：2
为深入解析西太平洋溶解有机碳的生物地球化学过程，本研究于2015年12月至2016年1月，开展了西太平洋上层水体有色溶解有机物（CDOM）吸收光谱和荧光光谱特征研究。研究结果表明，西太平洋上层水体CDOM吸收系数a（320）变化范围为0.01~1.07 m-1，平均值为0.18 m-1；其较高值位于100~200 m水层，表层的海水相对含量较低，主要以有机物的光化学分解为主。采用PARAFAC分析CDOM三维荧光光谱特征，得到1种类腐殖质组分C2（252（310 nm）/405 nm）及2种类蛋白组分C1（224（276 nm）/335 nm）和C3（224（260 nm）/300 nm），其中类腐殖质荧光组分占总荧光强度的11%~22%，蛋白质荧光组分占总荧光强度的78%~89%，蛋白质荧光中类色氨酸和类络氨酸组分对荧光强度的贡献相当。洋流在大尺度上控制西太平洋CDOM的分布特征，两流交界处和环流形成区域的CDOM相对含量较高，荧光信号较强。西太上层水体CDOM相对含量和荧光信息，与温度、盐度、DO和营养盐等理化因素之间的相关分析结果表明，CDOM主要成分类蛋白质的产生主要受上层水体初级生产过程控制。 相似文献
17.
对海水中锰的光化学反应及其影响因素进行了研究.实验结果表明,锰的光化学反应主要通过有机物为媒介进行,反应液中加入的有机物种类和浓度的改变会导致锰的光化学反应速率的改变.增加光强,有利于锰的光还原反应的进行.降低体系的pH值,可提高锰的光反应速率.锰在不同介质中光反应速率从大到小的顺序为:去离子水、人工海水、天然海水.此外,搅拌有利于锰的光反应的进行,但在体系分布已达均匀的前提下,搅拌速率的大小对锰的光反应速率几乎无影响.研究表明,通过光化学反应,海水中的锰会由四价的颗粒态转化为二价的可溶态,从而有利于浮游植物的吸收和生长. 相似文献
18.
We observed the origin, behavior, and flux of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), colored dissolved organic matter (CDOM), and dissolved inorganic nitrogen (DIN) in the subterranean estuary of a volcanic island, Jeju, Korea. The sampling of surface seawater and coastal groundwater was conducted in Hwasun Bay, Jeju, in three sampling campaigns (October 2010, January 2011, and June 2011). We observed conservative mixing of these components in this subterranean environment for a salinity range from 0 to 32. The fresh groundwater was characterized by relatively high DON, DIN, and CDOM, while the marine groundwater showed relatively high DOC. The DON and DIN fluxes through submarine groundwater discharge (SGD) in the groundwater of Hwasun Bay were estimated to be 1.3 × 105 and 2.9 × 105 mol d− 1, respectively. In the seawater of Hwasun Bay, the groundwater-origin DON was almost conservative while about 91% of the groundwater-origin DIN was removed perhaps due to biological production. The DON flux from the entire Jeju was estimated to be 7.9 × 108 mol yr− 1, which is comparable to some of the world's large rivers. Thus, our study highlights that DON flux through SGD is potentially important for delivery of organic nitrogen to further offshore while DIN is readily utilized by marine plankton in near-shore waters under N-limited conditions. 相似文献
19.
The southern Changjiang River Estuary has attracted considerable attention from marine scientists because it is a highly biologically active area and is biogeochemically significant.Moreover,land-ocean interactions strongly impact the estuary,and harmful algal blooms(HABs) frequently occur in the area.In October 2010 and May 2011,water samples of chromophoric dissolved organic matter(CDOM) were collected from the southern Changjiang River Estuary.Parallel factor analysis(PARAFAC) was used to assess the samples' CDOM composition using excitation-emission matrix(EEM) spectroscopy.Four components were identified:three were humic-like(C1,C2 and C3) and one was protein-like(C4).Analysis based on spatial and seasonal distributions,as well as relationships with salinity,Chl a and apparent oxygen utilization(AOU),revealed that terrestrial inputs had the most significant effect on the three humic-like Components C1,C2 and C3 in autumn.In spring,microbial processes and phytoplankton blooms were also important factors that impacted the three components.The protein-like Component C4 had autochthonous and allochthonous origins and likely represented a biologically labile component.CDOM in the southern Changjiang River Estuary was mostly affected by terrestrial inputs.Microbial processes and phytoplankton blooms were also important sources of CDOM,especially in spring.The fluorescence intensities of the four components were significantly higher in spring than in autumn.On average,C1,C2,C3,C4 and the total fluorescence intensity(TFI) in the surface,middle and bottom layers increased by123%–242%,105%–195%,167%–665%,483%–567% and 184%–245% in spring than in autumn,respectively.This finding corresponded with a Chl a concentration that was 16–20 times higher in spring than in autumn and an AOU that was two to four times lower in spring than in autumn.The humification index(HIX) was lower in spring that in autumn,and the fluorescence index(FI) was higher in spring than in autumn.This result indicated that the CDOM was labile and the biological activity was intense in spring. 相似文献
20.
The concentrations of dissolved organic carbon and nitrogen (DOC and DON, respectively) were measured in Shiraho fringing
reef (Japan), using a high-temperature catalytic-oxidation method. When the seawater on the reef flat (shallow lagoon) was
isolated from the surrounding ocean due to the low tide, the concentrations of DOC and DON on the reef flat were 66–75 and
4.8–5.7 μmol l−1, respectively. The DOC and DON concentrations were higher than those of the adjacent outer ocean (57–58 and 3.8 μmol l−1, respectively), suggesting that the coral reef functioned as a net source of dissolved organic matter for the surrounding
ocean. In order to investigate long-term bacterial decomposition of the reef-derived DOC (RF-DOC), the seawater samples collected
on the reef flat and at the adjacent ocean were incubated in the dark for 1 year. Regression analysis using an exponential
curve that considered two degradability pools (labile and refractory) fitted the mineralization of the RF-DOC very well (r
2 > 0.89). According to the regression analysis, the DOC produced on the reef flat was composed of the labile fraction of 63–94%
(average 77%) and the refractory fraction of 6–37% (average 23%). It was concluded that some of the DOC that was produced
in the coral reef ecosystem was exported to the surrounding ocean if the reef flat had a water residence time less than several
months. The exported organic matter may support microbial communities in the ocean as an energy source. 相似文献