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1.
长江口溶解有机物光漂白和光矿化表观量子产率 总被引：3，自引：1，他引：2
溶解有机物(DOM)经太阳光照射导致其吸光度(光漂白)和溶解有机碳(光矿化)损失,从而影响水体生态系统光学特性及碳循环。本文通过测定冬季长江口及其邻近海域DOM光降解表观量子产率(AQY),初步探讨了DOM光反应活性在河口及陆架海的变化特征。DOM光降解AQY由口内至口外逐渐递减,且有色溶解有机物(CDOM)光漂白速率是溶解有机碳(DOC)光矿化速率的10倍。Φble(CDOM光漂白表观量子产率)和Φmin(DOC光矿化平均量子产率)在最大浑浊带以东海域与盐度和SUVA254分别呈显著的线性负相关与正相关,表明DOM光反应活性在长江口外受物理混合影响为主,且陆源DOM光反应活性比海源高。此外,最大浑浊带下游DOM光降解AQY显著低于上游。DOM光降解速率随波长的变化呈现非高斯分布,且峰值出现在330 nm,积分结果表明UVA是DOM光降解的主要贡献者。本研究结果将为完善我国东海碳通量模型提供帮助。 相似文献
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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
3.
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
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利用在胶州湾中不同位置取得的3个水样,对溶解有色物质进行了不同时间的光脱色,探讨了有机物含量随脱色时间的变化趋势,得出有机物吸光系数和溶解有机碳随脱色时间的增长而呈指数减小,说明光脱色可以明显降低溶解有机物的含量。对不同光脱色程度的水样进行了光化学降解,测定了其主要产物一氧化碳的光致生成速率,发现在8个不同波段下一氧化碳光致生成速率与350 nm的吸光系数和溶解有机碳之间均有良好的线性关系。350 nm的吸光系数和溶解有机碳含量在一定程度上均可较好地表示海水中CDOM的含量。 相似文献
6.
红树林输送的溶解态陆源有机质是海洋中陆源有机质的主要来源之一,对其光降解和生物降解过程的研究有助于进一步了解红树林生态系统输出的有机质在近岸的归宿以及对近岸水体生物地球化学过程的影响,因此于2010年4月在海南省清澜港红树林采集间隙水,并进行了光降解和生物降解培养实验。分析了光培养(光降解)和暗培养过程(生物降解)中溶解态有机碳(DOC)、细菌以及溶解态木质素等的变化。结果显示经历128 d的暗培养后,DOC由初始的2 216 μmol/L下降至718 μmol/L,表明红树林间隙水的生物可利用性约为70%左右;经历11 d的自然光照后,DOC下降至800 μmol/L。木质素在光降解过程中的移除速率(-0.132 d-1)远高于生物降解过程(-0.008 d-1)。光培养中,木质素的下降速率高于总体DOC。不同系列溶解态木质素的下降速率不同,随着培养的进行,紫丁香基酚类(S)与香草基酚类(V)的比值(S/V)呈下降趋势,而V系列的酸醛比值((Ad/Al)v)呈上升的趋势。对比光培养和暗培养过程中DOC和木质素的变化可以得出生物消耗是引起红树林间隙水DOC从水体中移除的主要因素;而光照则是陆源有机质从水体中移除的主要因素;光培养和暗培养过程中细菌变化的差异表明光照可以促进细菌对溶解态有机碳的利用。与其他地区比较发现,海南红树林间隙水的光降解速率与热带河流(刚果河)相近,高于温带密西西比河流,降解过程中各参数的变化[S/V和(Ad/Al)v]与其他区域接近。 相似文献
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当前极端气候事件频发,引起了人们广泛的关注。然而,气候变化对中国典型河流溶解有机物(DOM)的影响尚且未得到充分的认识。2021年11月至2022年10月,每月于珠江下游广州段采集河水样品,并分析其中溶解有机碳(DOC)、发色溶解有机物(CDOM)和荧光溶解有机物(FDOM)的浓度和组成。采样期间, 2022年6月珠江流域遭遇百年一遇的洪水。结果显示,洪水大幅度降低了河水中的DOC和CDOM浓度,并提高了DOM的芳香化程度。尽管洪水对DOM浓度产生了明显的稀释效应,但通过分析FDOM组成,进一步发现FDOM中不同组分对洪水的响应存在较大差异。FDOM短激发波长(230～235nm)处的类蛋白质组分峰值在洪水期间出现高值;与此同时,长激发波长(280～285nm)的类蛋白质组分和激发波长在345nm处的类腐殖质组分峰值在洪水期间出现最低值。此外,与长江下游相比,珠江下游水体中往往具有较高的DOC和CDOM浓度、DOM芳香化程度以及CDOM分子量。研究将有助于进一步了解珠江等世界大河DOM浓度和组成的变化规律和控制机制,以及揭示极端洪水对大河DOM动态变化产生的影响。 相似文献
9.
珠江口磨刀门溶解有机物CDOM 三维荧光光谱特征 总被引：1，自引：0，他引：1
采用三维荧光对珠江口磨刀门夏秋季有色溶解有机物(CDOM)时空变化进行研究,分析其组成及荧光强度。结果表明, CDOM 三维荧光峰谱包括 UV 类腐殖质 A、陆源 Vis 类腐殖质 C 和海源 Vis类腐殖质M,以及类蛋白质T。在入海过程中,其组成未发生变化,但其荧光强度随盐度增加逐渐减小,反映了CDOM主要来源是陆源,并且主要受海水物理稀释控制,是一种典型的保守混合行为。在定点站位涨落潮周期中, CDOM的荧光强度不仅受到海水稀释的作用,表层水体CDOM受到紫外线的光降解作用,同时中层水体CDOM受到浮游植物的影响,反映了盐度、紫外线强度、生物活动对CDOM具有的共同影响。 相似文献
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北极孔斯峡湾表层沉积物中溶解有机质的来源与转化历史 总被引：7，自引：0，他引：7
在北极地区孔斯峡湾采集28个表层沉积物样品,测定了其中水溶性有机质(也称溶解有机质,DOM)的分子量分布、紫外/可见吸收光谱和三维荧光光谱特征,并利用平行因子分析(PARAFAC)模型对DOM的荧光组分和来源进行了解析。结果表明:孔斯峡湾表层沉积物中有色溶解有机质(CDOM)及其中的荧光溶解有机质(FDOM)含量均从内湾向外湾方向呈逐渐累积的趋势,但CDOM中的FDOM所占比例逐渐减小,与DOM趋于老龄化密切相关。沉积作用减弱以及长期的光化学降解和微生物降解作用对此起主要贡献,并导致腐殖质和小分子组分在沉积物DOM中所占的比例呈逐渐递增的趋势。沉积物DOM包含陆源类腐殖质、自生源类腐殖质和类蛋白等三个荧光组分,但是其组成比例空间差异很大。吸收光谱斜率比(SR)随自生源所占百分比增加而减小,随DOM腐殖质组分中陆源与自生源的比值增加而增加;腐殖化指数(HIX)随类腐殖质与类蛋白质比值和水深的增加而增加,生物源指数(BIX)随自生源比例增加而增加。峡湾沉积物DOM的组成和来源存在着高度的空间差异,在冰川湾区由水体颗粒有机质(POM)的近期转化和迁移而来,而在峡湾中央及口门附近以较老的腐殖质为优势,主要源于水体DOM长期迁移和转化。研究表明,FDOM/CDOM,SR,HIX和BIX等构成的CDOM光谱指纹信息可以作为揭露沉积物溶解有机质来源及迁移转化历史的工具,对探索海洋与冰川相互作用影响下的峡湾环境演变有着重要意义。 相似文献
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Reversed-phase liquid chromatography/mass spectrometry (LC/MS) is introduced as a new molecular fingerprinting technique for tracing terrigenous dissolved organic matter (DOM) and its photochemical decay in the ocean. DOM along a transect from the mangrove-fringed coast in Northern Brazil to the shelf edge was compared with mangrove-derived porewater DOM exposed to natural sunlight for 2–10 days in a photodegradation experiment. DOM was isolated from all samples via solid-phase extraction (C18) for LC/MS analysis. DOM in the estuary and ocean showed a bimodal mass distribution with two distinct maxima in the lower m/z range from 400 to 1000 Da (intensity-weighted average of 895 Da). Terrigenous porewater DOM from the mangroves was characterized by a broad molecular mass distribution over the detected range from 150 to 2000 Da (intensity-weighted average of 1130 Da). Polar compounds, i.e., those that eluted early in the reversed-phase chromatography, absorbed more UV light and had on average smaller molecular masses than the more apolar compounds. 相似文献
13.
高原湖泊溶解有机质的三维荧光光谱特性初步研究 总被引：9，自引：0，他引：9
提要近年来,荧光光谱技术被广泛应用于研究天然水体中溶解有机质(Dissolved Organic Matter,DOM)的物理化学特性。为了理解高原湖泊中DOM的组成、荧光光谱特性及其在湖泊水体中的垂直分布情况,作者利用荧光发射光谱、三维荧光光谱研究云贵高原湖泊红枫湖和百花湖中的DOM。结果显示,高原湖泊DOM主要表现为类富里酸荧光,包括可见区和紫外区两种类型的荧光峰,各种天然水体中都有报道的类蛋白荧光在红枫湖DOM中并不明显,而在百花湖DOM中则有较强的类蛋白荧光。溶解有机质所含三种类型荧光峰(PeakA:紫外区类富里酸荧光峰;PeakB:可见区类富里酸荧光峰;PeakC:类蛋白荧光峰)的荧光强度与溶解有机碳之间没有明显的线性相关关系,可能与高原湖泊水体pH值、DOM在湖泊不同深度由于受到光降解、微生物降解等作用存在差异等因素有关。与有机质结构和成熟度有关的荧光峰比值r(A,C)在1.40—2.09范围内,红枫湖南湖、百花湖DOM样品的r(A,C)值随着水体深度有下降的趋势,而红枫湖北湖DOM的r(A,C)值则随着水体深度有较大起伏,揭示了高原湖泊水体中DOM的结构以及分布情况存在差异。另外,r(A,C)值与pH之间具有良好的正相关关系,其相关系数红枫湖南湖DOM为0.95,百花湖两个采样点DOM分别为0.67、0.75,而红枫湖北湖DOM则显示出一定的负相关性(R2=0.45)。 相似文献
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Seasonal variations in dissolved organic carbon concentrations and characteristics in a shallow coastal bay 总被引：8，自引：0，他引：8
Dissolved organic matter (DOM) composition and dynamics in temperate shallow coastal bays are not well described although these bays may be important as local sources of organic carbon to ocean waters and are often sites of economically-important fisheries and aquaculture. In this study surface water samples were collected on a monthly to bi-monthly basis over two years from a mid-Atlantic coastal bay (Chincoteague Bay, Virginia and Maryland, USA). Dissolved organic carbon (DOC) concentrations and light absorbance characteristics were measured on sterile-filtered water, and high-molecular weight (> 1 kDa) dissolved OM (DOM) was isolated to determine stable isotope composition and molecular-level characteristics. Our time series encompassed both a drought year (2002) and a year of above-average rainfall (2003). During the dry year, one of our sites developed a very intense bloom of the brown tide organism Aureococcus anophagefferens while during the wet year there were brown tide bloom events at both of our sampling sites. During early spring of the wet year, there were higher concentrations of > 1 kDa DOC; this fraction represented a larger proportion of overall DOC and appeared considerably more allochthonous. Based upon colored dissolved organic matter (CDOM) and high-molecular weight DOM analyses, the development of extensive phytoplankton blooms during our sampling period significantly altered the quality of the DOM. Throughout both years Chincoteague Bay had high DOC concentrations relative to values reported for the coastal ocean. This observation, in conjunction with the observed effects of phytoplankton blooms on DOM composition, indicates that Chincoteague Bay may be a significant local source of “recently-fixed” organic carbon to shelf waters. Estimating inputs of DOC from Chincoteague Bay to the Mid-Atlantic Bight suggests that shallow productive bays should be considered in studies of organic carbon on continental shelves. 相似文献
15.
天然水环境中的溶解有机物及其光化学降解对重金属生物可利用性的影响 总被引：1，自引：0，他引：1
溶解有机物(DOM)在控制水生生态系统的化学、生物和物理特性中起着重要的作用.DOM不仅能够结合黏土颗粒,而且也能结合对环境和生物有重要影响的Hg,Cu,Pb,Cd,Ni等重金属和有机污染物,从而改变这些物质的迁移、生物可利用性和毒性.本文综述了天然水环境中DOM与重金属的相互作用和对其生物可利用性的影响,并对影响DOM光化学降解的因素及其对重金属生物可利用性的影响做了总结.已有的研究表明:DOM的结构、分子量、浓度、重金属种类、水环境条件等均会影响到DOM与重金属污染物的相互作用;光化学降解会显著改变DOM与重金属的相互作用,从而使其生物可利用性发生变化. 相似文献
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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
17.
Stocks and dynamics of dissolved and particulate organic matter in the southern Ross Sea, Antarctica
Craig A. Carlson Dennis A. Hansell Edward T. Peltzer Walker O. Smith Jr. 《Deep Sea Research Part II: Topical Studies in Oceanography》2000,47(15-16)
Dissolved and particulate organic matter was measured during six cruises to the southern Ross Sea. The cruises were conducted during late austral winter to autumn from 1994 to 1997 and included coverage of various stages of the seasonal phytoplankton bloom. The data from the various years are compiled into a representative seasonal cycle in order to assess general patterns of dissolved organic matter (DOM) and particulate organic matter (POM) dynamics in the southern Ross Sea. Dissolved organic carbon (DOC) and particulate organic carbon (POC) were at background concentrations of approximately 42 and 3 μM C, respectively, during the late winter conditions in October. As the spring phytoplankton bloom progressed, organic matter increased, and by January DOC and POC reached as high as 30 and 107 μM C, respectively, in excess of initial wintertime conditions. Stocks and concentrations of DOC and POC returned to near background values by autumn (April). Approximately 90% of the accumulated organic matter was partitioned into POM, with modest net accumulation of DOM stocks despite large net organic matter production and the dominance of Phaeocystis antarctica. Changes in NO3 concentration from wintertime values were used to calculate the equivalent biological drawdown of dissolved inorganic carbon (DICequiv). The fraction of DICequiv drawdown resulting in net DOC production was relatively constant (ca. 11%), despite large temporal and spatial variability in DICequiv drawdown. The C : N (molar ratio) of the seasonally produced DOM had a geometric mean of 6.2 and was nitrogen-rich compared to background DOM. The DOM stocks that accumulate in excess of deep refractory background stocks are often referred to as “semi-labile” DOM. The “semi-labile” pool in the Ross Sea turns over on timescales of about 6 months. As a result of the modest net DOM production and its lability, the role DOM plays in export to the deep sea is small in this region. 相似文献
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Tracing dissolved organic matter in aquatic environments using a new approach to fluorescence spectroscopy 总被引：34，自引：0，他引：34
Dissolved organic matter (DOM) is a complex and poorly understood mixture of organic polymers that plays an influential role in aquatic ecosystems. In this study we have successfully characterised the fluorescent fraction of DOM in the catchment of a Danish estuary using fluorescence excitation–emission spectroscopy and parallel factor analysis (PARAFAC). PARAFAC aids the characterisation of fluorescent DOM by decomposing the fluorescence matrices into different independent fluorescent components. The results reveal that at least five different fluorescent DOM fractions present (in significant amounts) in the catchment and that the relative composition is dependent on the source (e.g. agricultural runoff, forest soil, aquatic production). Four different allochthonous fluorescent groups and one autochthonous fluorescent group were identified. The ability to trace the different fractions of the DOM pool using this relatively cheap and fast technique represents a significant advance within the fields of aquatic ecology and chemistry, and will prove to be useful for catchment management. 相似文献
19.
Dissolved organic matter (DOM) and dissolved copper-organic complexes were isolated from the estuarine waters of Narragansett Bay, RI, using reverse-phase liquid chromatography (RPLC). Different types of reverse-phase BOND ELUT columns (Analytichem International), including C2, C18 and phenyl-bonded phases, were studied to determine their adsorption efficiency for extracting DOM. Extraction efficiencies followed the order phenyl > C18 > C2, and phenyl − C18 > C2 for DOM and organic copper, respectively. However, comparisons of BOND ELUT and C18 SEP-PAK (Waters Associates) columns indicated that SEP-PAK columns were the most efficient when both DOM and organic copper were considered. Chromatographic profiles of the isolated DOM obtained using high-performance liquid chromatography were similar in elution characteristics and resembled chromatograms typical of fulvic acid. The UV-absorption characteristics of the DOM showed small differences and suggested that the different reverse-phase columns isolated material that was qualitatively similar.Copper-organic complexes isolated using C18 RPLC were studied to examine the dissociation of organically bound copper in seawater as the pH is lowered. Only a small amount of the complexed copper was displaced by the H+ with about 40% of the copper remaining bound at pH 3. However, the chromatographic elution behavior of the DOM and organic copper was significantly altered under acidic conditions as a result of protonation of acidic functional sites on the organic matter. 相似文献