沉积物间隙水中CDOM光学特性与河口CDOM光化学反应研究
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摘要
海洋有色溶解有机物(CDOM)作为溶解有机物(DOM)的主要成分及海洋碳循环的关键环节,近年来受到海洋学家的广泛重视。本论文围绕海洋CDOM的两个潜在来源——沉积物的再悬浮作用与雨水输入,以及一个关键的去除途径——光化学降解展开研究,利用最新的三维荧光光谱(EEMs)分析手段,结合吸收光谱以及溶解有机碳(DOC)的测定,分析了中国华南地区河口近海沉积物间隙水中CDOM的光学特性及底质再悬浮作用作为海水中CDOM来源的可能性;在国内首次观测了雨水中CDOM的荧光光谱特征,探讨了其对大气化学的意义及对海洋CDOM通量的贡献;开展了河口区CDOM在天然太阳辐照下的光化学降解研究,探讨光化学反应作为CDOM降解转化途径的重要性,以期为进一步研究河口近海溶解有机物的源汇格局、迁移转化及循环机制提供更完整的参考资料。本研究获取的主要结果如下:
1)厦门湾、兴化湾、湄洲湾及北部湾表层沉积物间隙水中CDOM的EEMs大体相似,观测到的主要荧光谱峰有类腐殖质荧光峰(A、C)以及类蛋白质荧光峰(包括类色氨酸荧光峰B、S及类酪氨酸荧光峰T、R),这些谱峰均成对出现。强类蛋白质荧光的出现,揭示了早期成岩过程中大量含色氨酸和酪氨酸等芳香结构的溶解有机质在表层沉积物中的积累。反映陆源特征的类腐殖质荧光峰C随不同海湾和不同站点而变化,而代表海洋来源的荧光峰M在上述海域间隙水中均不明显。
2)沉积物间隙水中CDOM的平均浓度(以λex/λem=350nm/450nm的荧光强度表示)以湄洲湾最大,兴化湾次之,厦门湾和北部湾最低,表明陆源有机物质的输入对湄洲湾和兴化湾中的沉积物影响较大,而对厦门湾和北部湾的影响较小。不同海域各荧光谱峰之间的荧光强度比值差别大,说明其来源或组成存在差异。4个海域沉积物间隙水CDOM的荧光指数均大于1.5,接近1.9,指示这些海域沉积物中溶解有机物的性质受微生物活动的影响较大,尤其是兴化湾表层沉积物中微生物活动更强。
3)对九龙江口沉积物样品进行的室内再悬浮模拟实验表明,对给定的站位,CDOM的相对荧光强度和DOC含量分布变化均表现为间隙水最高,再悬浮样次之,底层水最低。不同站位之间,底层水和再悬浮水样中CDOM相对荧光强度随盐度的降低而增加,从海端向河端增加的趋势明显。EEMs分析表明,再悬浮作用可释放类腐殖质与类蛋白质荧光物质到底层水中,表明底质再悬浮将是近岸水体中CDOM的一个重要来源。再悬浮样品中EEMs的荧光团同时表现出相应底层水和间隙水的特征,但是荧光峰(峰A和峰C)的最大激发和发射波长更接近底层水中相应荧光团。与间隙水相比,则发生谱峰位置的蓝移。近海端样品中海源荧光峰M明显,随着由海端向河端盐度逐渐降低,峰M逐渐消失,表明峰M属于海洋自生来源。DOM的荧光指数在1.61-1.93之间变化,表明近海端样品DOM,主要为生物来源,而近河端样品DOM主要为陆源输入,或者为陆源与生物活动的共同作用。
4)2007年夏、秋季,对取自九龙江口的CDOM水样进行了为期约一周的天然日光辐照下的光化学降解实验,在这些水样中观测到的类腐殖质荧光及类蛋白质荧光等均在日光照射下发生明显的光化学降解,到实验结束时,荧光损失最大可达90%,而相应的对照组中各荧光谱峰的荧光几乎不变化。陆源特征的荧光峰C较峰A更易受太阳辐射的影响而更易发生光化学降解。随辐照时间增加,CDOM的吸收系数a(250)及a(280)也呈不断降低的趋势,至辐照实验结束时,吸收损失最大约1/2,吸收损失的速率明显慢于荧光。荧光和吸收损失主要发生在＜320 nm的短紫外波段。
5)与对照组相比,反映CDOM分子组成和平均分子量的A_(250)/A_(350)比值经过日光辐照后变大,表明光化学反应可把大分子的CDOM降解为小分子的CDOM,其平均分子粒径变小,表明光降解可能是陆源CDOM入海后的一个重要“归宿”。但与荧光和吸收特性相比,DOC光化学降解的程度较小,说明吸光的大分子DOC只是转变为不(弱)吸光的小分子DOC。低盐度站位CDOM水样的光化学降解速率高于中盐度站位样品。
6)雨水中CDOM的光学特征表明,在厦门湾采集的所有雨水样都观测到CDOM,其吸收光谱随波长增加呈指数衰减。多雨期间雨水中CDOM的相对含量高。雨水样的EEMs光谱揭示有3类荧光峰(2个类腐殖质荧光和3个类蛋白质荧光)存在,其中2个类腐殖质荧光均与吸收系数a(300)之间具很强的正相关关系,表明控制其吸收特性的基团可能与控制其荧光特性的基团具有相同性质。人为活动或陆源可能是雨水中CDOM的主要贡献者。pH在5-7范围内几乎不影响CDOM中荧光峰所处的位置,但是,随pH值从5增加到9,各荧光峰荧光强度及吸收系数均有增加。雨水样中较高浓度CDOM的存在,在受大气水体影响的太阳辐射的光谱衰减中可能起着潜在的重要作用,同时也是海域CDOM不可忽视的一个源通量。
Marine chromophoric dissolved organic matter(CDOM) was main component of dissolved organic matter(DOM),and played a key role in marine carbon cycle,widely attention was paid to by most oceangraphers recently.The paper enclosed the two potential sources,that was resuspension of sediments and rain contribution,and a key removal path,that was photochemical degradation.We employed new excitation-emission matrix fluorescence spectroscopy(EEMs),associated with absorption spectrum and dissolved organic carbon(DOC) investigate the optical chaeacteristics of CDOM in pore waters from Chinese estuarine and coastal sediments and analysed that it was possible that resuspension was a source of marine CDOM.And the study observed firstly characteristics of EEMs of CDOM in rainwater in china, and discussed it was significant to atmospheric waters and contrubition to marine CDOM flux.And,this study developed the photodegradation of CDOM from estuarine region exposure on solar radiation,pointed out it was important that photochemical reaction was a transformation approach of CDOM,provided the more complete references/information to further research into the source and sink,and removal and transfer, and cycle mechanism of dissolved organic matter in coastal an estuarine region.The main results were as follows:
1) Characteristics of EEMs of CDOM in surface sediments were all similar from Xiamen Bay and Xinghua Bay and Meizhou Bay and Beibu Gulf,main fluorescence peaks including humic-like fluorescence peaks(e.g.Peak A and C) and protein-like fluorescence peaks(such as tryptophan-like fluorescence B and S and tyrosine-like fluorescence T and R ) were observed,these peaks appeared to occur in pairs.The emergence of intensive protein-like fluorescence indicated dissolved organic matter with aromatic character such as tryptophan and tyrosine deposited in surface sediment during early diagenesis.The humic-like fluorescence peak C reflecting terrestrial source varied with different bays and sites,while the humic-like fluorescence peak M reflecting marine source was not evident in these forementioned sites.
2) The maxima of average concentration of CDOM in sediment pore waters occurred in Meizhou Bay, and subsequently Xinghua Bay,and then the minima of that appeared in Xiamen Bay and Beibu Gulf, indicating the most influence of the input of terrestrial organic matter on the sediments derived from Meizhou Bay and Xinghua Bay.The ratios of fluorescence intensities of fluorescence peaks in these regions existed in many differences,illuminating there were differences in the sources and constitutes.The fluorescence indexes of CDOM in pore waters from four coastal regions were all more than 1.5,closed to 1.9,showing properties of dissolved organic matter went through huge disturbance of microorganism, especially in surface sediments from Xinghua Bay.
3) The simulative experiment in laboratory devided from Jiulong Estuary was employed to study fluorescence characteristics of CDOM readily released from sediment particles during episodes of resuspension,and bottom waters and surface sediment pore waters were compared in all corresponding sites.Results showed,for a given site,both relative intensities of CDOM fluorescence and concentrations of DOC have the same trend with the maxima in the pore waters and the lowest in the bottom waters. Relative intensities of CDOM fluorescence increased with salinity descreasing from marine to riverine environments in bottom waters and resuspended samples.EEMs showed several types of fluorescence signals observed,including humic-like and protein-like fluorescence for all samples,and simulated experimentation also showed humic-like and protein-like material were released to bottom waters by resuspension,indicating sediment resuspension would be an important source of CDOM from coastal waters.For a given site,positions of fluorescence peaks(e.g.peak A and peak C) in pore waters were red-shifted,compared to their respective bottom waters.EEMs for all resuspended samples exhibited mixed characteristics between corresponding bottom and pore waters,but Ex/Em-max of peak A and C was very close to that in bottom waters,and observed blue-shift of peak positions in comparison with pore-water samples.Peak M was strong in marine environment,and gradually disappeared with salinity descreasing from marine to riverine environments,and peak M and C ratios also lowered in bottomwaters and resuspended samples,indicating peak M was derived from marine origin.The fluorescence index of DOM varied from 1.61 to 1.93,suggesting DOM in marine environment was dominating biological origin,DOM in riverine environment was controlled by terrestrial input,or was associated with terrestrial substance and microbial activities.
4) Photochemical degradation experiments of the samples from Jiulong estuary exposure on solar radiation were performed in summer and fall 2007,the humic-like and protein-like fluorescence observed in the samples photodegradated obviously when exposed on solar irradiation,and fluorescence loss could reach 90%approximately in the end of the experiment,while the fluorescence of any fluorescence peaks of the samples controlled hardly changed.Peak C was more liable to solar effect to photodegradate than peak A.Absorption coefficients a(250) and a(280) of CDOM decreased with increasing radiation time,and absorption loss could arrive at 50%when the experiment ended.The rate of the fluorescence loss was faster than that of absorption loss.The loss of fluorescence and absorption mainly took place at less than 320 nm.
5) Compared with the controlled samples,the ratios of A_(250) and A_(350) reflecting molecular constitutes and average molecular weight of CDOM increased during exposure,making clear that photochemical reaction transfered the CDOM of large molecular weight into the CDOM of small molecule weight,and the average molecular size became small,explaining photodegradation was possibly an important sink to terrestrial CDOM entering into the coastal sea.The photodegradation of DOC was slight comparison with fluorescence and absorption of CDOM,suggesting DOC absorbing light of large molecular size was transformed into DOC nonabsorbing light of small molecular size.The photodegradation rate of CDOM samples with low salinity was faster than that of CDOM samples with high salinity.
6) All rainwater samples contained CDOM collected in Xiamen Bay,the absorptance spectra of CDOM in the samples decreased exponentially with wavelength.The CDOM content was high during abundant rainfall.EEMs spectra showed 5 types fluorescence peak(2 humic-like fluorescence and 3 protein-like fluorescence) in rainwater samples,there was strong positive correlation between the two humic-like fluorescence and absortance coefficient at 300 nm,suggesting that these optical properties are directly interrelated and that the compounds responsible for absorbance might be the same as those responsible for fluorescence.Anthropogenic or terrestrial sources were impotant contributors to CDOM livels in precipitation.The pH values didn't affect the positions of the fluorescence peaks,but when pH value varied from 5 to 9,intensity of every fluorescence peak and absorption coefficient were both increasing.The presence of highly absorbing and fluorescing CDOM in rainwater had significant ramifications in atmospheric chemistry and might play a previously unrecognized role in the wavelength dependent spectral attenuation of solar radiation by atmospheric waters,at the same time,it also was an unneglectable source to CDOM from coastal sea.
1)厦门湾、兴化湾、湄洲湾及北部湾表层沉积物间隙水中CDOM的EEMs大体相似,观测到的主要荧光谱峰有类腐殖质荧光峰(A、C)以及类蛋白质荧光峰(包括类色氨酸荧光峰B、S及类酪氨酸荧光峰T、R),这些谱峰均成对出现。强类蛋白质荧光的出现,揭示了早期成岩过程中大量含色氨酸和酪氨酸等芳香结构的溶解有机质在表层沉积物中的积累。反映陆源特征的类腐殖质荧光峰C随不同海湾和不同站点而变化,而代表海洋来源的荧光峰M在上述海域间隙水中均不明显。
2)沉积物间隙水中CDOM的平均浓度(以λex/λem=350nm/450nm的荧光强度表示)以湄洲湾最大,兴化湾次之,厦门湾和北部湾最低,表明陆源有机物质的输入对湄洲湾和兴化湾中的沉积物影响较大,而对厦门湾和北部湾的影响较小。不同海域各荧光谱峰之间的荧光强度比值差别大,说明其来源或组成存在差异。4个海域沉积物间隙水CDOM的荧光指数均大于1.5,接近1.9,指示这些海域沉积物中溶解有机物的性质受微生物活动的影响较大,尤其是兴化湾表层沉积物中微生物活动更强。
3)对九龙江口沉积物样品进行的室内再悬浮模拟实验表明,对给定的站位,CDOM的相对荧光强度和DOC含量分布变化均表现为间隙水最高,再悬浮样次之,底层水最低。不同站位之间,底层水和再悬浮水样中CDOM相对荧光强度随盐度的降低而增加,从海端向河端增加的趋势明显。EEMs分析表明,再悬浮作用可释放类腐殖质与类蛋白质荧光物质到底层水中,表明底质再悬浮将是近岸水体中CDOM的一个重要来源。再悬浮样品中EEMs的荧光团同时表现出相应底层水和间隙水的特征,但是荧光峰(峰A和峰C)的最大激发和发射波长更接近底层水中相应荧光团。与间隙水相比,则发生谱峰位置的蓝移。近海端样品中海源荧光峰M明显,随着由海端向河端盐度逐渐降低,峰M逐渐消失,表明峰M属于海洋自生来源。DOM的荧光指数在1.61-1.93之间变化,表明近海端样品DOM,主要为生物来源,而近河端样品DOM主要为陆源输入,或者为陆源与生物活动的共同作用。
4)2007年夏、秋季,对取自九龙江口的CDOM水样进行了为期约一周的天然日光辐照下的光化学降解实验,在这些水样中观测到的类腐殖质荧光及类蛋白质荧光等均在日光照射下发生明显的光化学降解,到实验结束时,荧光损失最大可达90%,而相应的对照组中各荧光谱峰的荧光几乎不变化。陆源特征的荧光峰C较峰A更易受太阳辐射的影响而更易发生光化学降解。随辐照时间增加,CDOM的吸收系数a(250)及a(280)也呈不断降低的趋势,至辐照实验结束时,吸收损失最大约1/2,吸收损失的速率明显慢于荧光。荧光和吸收损失主要发生在＜320 nm的短紫外波段。
5)与对照组相比,反映CDOM分子组成和平均分子量的A_(250)/A_(350)比值经过日光辐照后变大,表明光化学反应可把大分子的CDOM降解为小分子的CDOM,其平均分子粒径变小,表明光降解可能是陆源CDOM入海后的一个重要“归宿”。但与荧光和吸收特性相比,DOC光化学降解的程度较小,说明吸光的大分子DOC只是转变为不(弱)吸光的小分子DOC。低盐度站位CDOM水样的光化学降解速率高于中盐度站位样品。
6)雨水中CDOM的光学特征表明,在厦门湾采集的所有雨水样都观测到CDOM,其吸收光谱随波长增加呈指数衰减。多雨期间雨水中CDOM的相对含量高。雨水样的EEMs光谱揭示有3类荧光峰(2个类腐殖质荧光和3个类蛋白质荧光)存在,其中2个类腐殖质荧光均与吸收系数a(300)之间具很强的正相关关系,表明控制其吸收特性的基团可能与控制其荧光特性的基团具有相同性质。人为活动或陆源可能是雨水中CDOM的主要贡献者。pH在5-7范围内几乎不影响CDOM中荧光峰所处的位置,但是,随pH值从5增加到9,各荧光峰荧光强度及吸收系数均有增加。雨水样中较高浓度CDOM的存在,在受大气水体影响的太阳辐射的光谱衰减中可能起着潜在的重要作用,同时也是海域CDOM不可忽视的一个源通量。
Marine chromophoric dissolved organic matter(CDOM) was main component of dissolved organic matter(DOM),and played a key role in marine carbon cycle,widely attention was paid to by most oceangraphers recently.The paper enclosed the two potential sources,that was resuspension of sediments and rain contribution,and a key removal path,that was photochemical degradation.We employed new excitation-emission matrix fluorescence spectroscopy(EEMs),associated with absorption spectrum and dissolved organic carbon(DOC) investigate the optical chaeacteristics of CDOM in pore waters from Chinese estuarine and coastal sediments and analysed that it was possible that resuspension was a source of marine CDOM.And the study observed firstly characteristics of EEMs of CDOM in rainwater in china, and discussed it was significant to atmospheric waters and contrubition to marine CDOM flux.And,this study developed the photodegradation of CDOM from estuarine region exposure on solar radiation,pointed out it was important that photochemical reaction was a transformation approach of CDOM,provided the more complete references/information to further research into the source and sink,and removal and transfer, and cycle mechanism of dissolved organic matter in coastal an estuarine region.The main results were as follows:
1) Characteristics of EEMs of CDOM in surface sediments were all similar from Xiamen Bay and Xinghua Bay and Meizhou Bay and Beibu Gulf,main fluorescence peaks including humic-like fluorescence peaks(e.g.Peak A and C) and protein-like fluorescence peaks(such as tryptophan-like fluorescence B and S and tyrosine-like fluorescence T and R ) were observed,these peaks appeared to occur in pairs.The emergence of intensive protein-like fluorescence indicated dissolved organic matter with aromatic character such as tryptophan and tyrosine deposited in surface sediment during early diagenesis.The humic-like fluorescence peak C reflecting terrestrial source varied with different bays and sites,while the humic-like fluorescence peak M reflecting marine source was not evident in these forementioned sites.
2) The maxima of average concentration of CDOM in sediment pore waters occurred in Meizhou Bay, and subsequently Xinghua Bay,and then the minima of that appeared in Xiamen Bay and Beibu Gulf, indicating the most influence of the input of terrestrial organic matter on the sediments derived from Meizhou Bay and Xinghua Bay.The ratios of fluorescence intensities of fluorescence peaks in these regions existed in many differences,illuminating there were differences in the sources and constitutes.The fluorescence indexes of CDOM in pore waters from four coastal regions were all more than 1.5,closed to 1.9,showing properties of dissolved organic matter went through huge disturbance of microorganism, especially in surface sediments from Xinghua Bay.
3) The simulative experiment in laboratory devided from Jiulong Estuary was employed to study fluorescence characteristics of CDOM readily released from sediment particles during episodes of resuspension,and bottom waters and surface sediment pore waters were compared in all corresponding sites.Results showed,for a given site,both relative intensities of CDOM fluorescence and concentrations of DOC have the same trend with the maxima in the pore waters and the lowest in the bottom waters. Relative intensities of CDOM fluorescence increased with salinity descreasing from marine to riverine environments in bottom waters and resuspended samples.EEMs showed several types of fluorescence signals observed,including humic-like and protein-like fluorescence for all samples,and simulated experimentation also showed humic-like and protein-like material were released to bottom waters by resuspension,indicating sediment resuspension would be an important source of CDOM from coastal waters.For a given site,positions of fluorescence peaks(e.g.peak A and peak C) in pore waters were red-shifted,compared to their respective bottom waters.EEMs for all resuspended samples exhibited mixed characteristics between corresponding bottom and pore waters,but Ex/Em-max of peak A and C was very close to that in bottom waters,and observed blue-shift of peak positions in comparison with pore-water samples.Peak M was strong in marine environment,and gradually disappeared with salinity descreasing from marine to riverine environments,and peak M and C ratios also lowered in bottomwaters and resuspended samples,indicating peak M was derived from marine origin.The fluorescence index of DOM varied from 1.61 to 1.93,suggesting DOM in marine environment was dominating biological origin,DOM in riverine environment was controlled by terrestrial input,or was associated with terrestrial substance and microbial activities.
4) Photochemical degradation experiments of the samples from Jiulong estuary exposure on solar radiation were performed in summer and fall 2007,the humic-like and protein-like fluorescence observed in the samples photodegradated obviously when exposed on solar irradiation,and fluorescence loss could reach 90%approximately in the end of the experiment,while the fluorescence of any fluorescence peaks of the samples controlled hardly changed.Peak C was more liable to solar effect to photodegradate than peak A.Absorption coefficients a(250) and a(280) of CDOM decreased with increasing radiation time,and absorption loss could arrive at 50%when the experiment ended.The rate of the fluorescence loss was faster than that of absorption loss.The loss of fluorescence and absorption mainly took place at less than 320 nm.
5) Compared with the controlled samples,the ratios of A_(250) and A_(350) reflecting molecular constitutes and average molecular weight of CDOM increased during exposure,making clear that photochemical reaction transfered the CDOM of large molecular weight into the CDOM of small molecule weight,and the average molecular size became small,explaining photodegradation was possibly an important sink to terrestrial CDOM entering into the coastal sea.The photodegradation of DOC was slight comparison with fluorescence and absorption of CDOM,suggesting DOC absorbing light of large molecular size was transformed into DOC nonabsorbing light of small molecular size.The photodegradation rate of CDOM samples with low salinity was faster than that of CDOM samples with high salinity.
6) All rainwater samples contained CDOM collected in Xiamen Bay,the absorptance spectra of CDOM in the samples decreased exponentially with wavelength.The CDOM content was high during abundant rainfall.EEMs spectra showed 5 types fluorescence peak(2 humic-like fluorescence and 3 protein-like fluorescence) in rainwater samples,there was strong positive correlation between the two humic-like fluorescence and absortance coefficient at 300 nm,suggesting that these optical properties are directly interrelated and that the compounds responsible for absorbance might be the same as those responsible for fluorescence.Anthropogenic or terrestrial sources were impotant contributors to CDOM livels in precipitation.The pH values didn't affect the positions of the fluorescence peaks,but when pH value varied from 5 to 9,intensity of every fluorescence peak and absorption coefficient were both increasing.The presence of highly absorbing and fluorescing CDOM in rainwater had significant ramifications in atmospheric chemistry and might play a previously unrecognized role in the wavelength dependent spectral attenuation of solar radiation by atmospheric waters,at the same time,it also was an unneglectable source to CDOM from coastal sea.
引文
Blough,N.V.and Green,S.A.,1995:Spectroscopic characterization and remote sensing of nonliving organic matter[A].In:Role of Non Living Organic Matter in the Earth's Carbon Cycle[C].Wiley &Sons Ltd.
Bricaud A.Absorption by dissolved organic matter of the sea(Yellow substance)in the UV and visible domains[J].Limnol.Oceanogr.,1981,26:43-53.
Cappiello A.et al.Molecular characterization of the water soluble organic compounds in fogwater by ESIMS/MS[J].Environ.Sci.Technol.2003,37:1229-1240.
Chin Y-P,Alken G,O'Loughlin E.Molecular weight,polydispersity,and spectroscopic properties of aquatic humic substances[J].Environ.Sci.Technol,1994,28:1853-1858.
Chin Y-P,Traina S,Swank C.Abundance and properties of dissolved organic matter in pore waters of a freshwater wetland[J].Limnol.Oceanogr.1998,43:1287-1296.
Coble P G.Characterization of marine and terrestrial DOM in seawater using excitationemission matrix spectroscopy[J].Mar.Chem.1996,51:325-346. Decesari S, Facchini M C, Fuzzi S, et al. The water soluble organic component of size segragated aerosol, cloud water and wet deposition from Jeju Island during ACE Asia[J]. Atmos. Environ, 2005,39: 211-222.
Decesari S, Facchini M C, Matta E, et al. Water soluble organic compounds formed by oxidation of soot[J]. Atmos. Environ. 2002, 36: 1827-1832.
Diallo M S, Simpson A, Gassman P, et al. 3-D structural modeling of humic acids through experimental characterization, computer assisted structure elucidation and atomistic simulations. 1. Chelsea soil humic acid[J]. Environ. Sci. Technol. 2003, 37: 1783-1793.
Feng J & Moller D. Characterization of water-soluble macromolecular substances in cloud water[J]. J Atmos Chem, 2004,48:217-233.
Green S A, Blough N V. Optical absorption and fluorescence properties of chromophoric dissolved organic matter in natural waters[J]. Limnol Oceanogr, 1994, 38:1 903-1 916.
Kieber R J, Hardison D R, Whitehead R F, et al. Photochemical production of Fe(II) in rainwater[J]. Environ. Sci. Technol. 2003, 37:4610-4616.
Kieber R J, Skrabal S A, Smith B, et al. Organic complexation of Fe(II) and its impact on the redox cycling of iron in rain[J]. Environ. Sci. Technol. 2005, 39:1576-1583.
Kieber R J, Skrabal S A, Smith B, et al. Redox speciation of copper in rainwater: Temporal variability and atmospheric deposition[J]. Environ. Sci. Technol. 2004, 38: 3587-3594.
Kieber R J, Whitehead R F, Reid S N, et al. Chromophoric dissolved organic matter (CDOM) in rainwater, Southeastern North Carolina, USA[J]. Journal of Atmospheric Chemistry .2006,54:21-41.
Kieber R J, Willey J D, Zvalaren S D. Chromium speciation in rainwater: Temporal variability and atmospheric deposition[J]. Environ Sci Technol, 2002, 36:5321-5327.
McKnight D M, Boyer E W, Westerhoff P K, et al. Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity[J]. Limnol Oceanogr, 2001, 46(1): 38-48.
Witt M L I, Skrabal S, Kieber R, et al. Photochemistry of Cu complexed with chromophoric dissolved organic matter: implications for Cu speciation in rainwater[J]. J Atmos Chem, DOI 10.1007/s10874-007-9079-5.
Zepp R G. Solar Ultraviolet Radiation And Aquatic Carbon, Nitrogen, Sulfur And Metals Cycles[A]. In: UV Effects In Aquatic Organisms And Ecosystems[C], E.W.Helbling & H. Zagarese (eds), Royal Society of Chemistry, Cambridge UK, 2002, pp. 137-183.
Bricaud A.Absorption by dissolved organic matter of the sea(Yellow substance)in the UV and visible domains[J].Limnol.Oceanogr.,1981,26:43-53.
Cappiello A.et al.Molecular characterization of the water soluble organic compounds in fogwater by ESIMS/MS[J].Environ.Sci.Technol.2003,37:1229-1240.
Chin Y-P,Alken G,O'Loughlin E.Molecular weight,polydispersity,and spectroscopic properties of aquatic humic substances[J].Environ.Sci.Technol,1994,28:1853-1858.
Chin Y-P,Traina S,Swank C.Abundance and properties of dissolved organic matter in pore waters of a freshwater wetland[J].Limnol.Oceanogr.1998,43:1287-1296.
Coble P G.Characterization of marine and terrestrial DOM in seawater using excitationemission matrix spectroscopy[J].Mar.Chem.1996,51:325-346. Decesari S, Facchini M C, Fuzzi S, et al. The water soluble organic component of size segragated aerosol, cloud water and wet deposition from Jeju Island during ACE Asia[J]. Atmos. Environ, 2005,39: 211-222.
Decesari S, Facchini M C, Matta E, et al. Water soluble organic compounds formed by oxidation of soot[J]. Atmos. Environ. 2002, 36: 1827-1832.
Diallo M S, Simpson A, Gassman P, et al. 3-D structural modeling of humic acids through experimental characterization, computer assisted structure elucidation and atomistic simulations. 1. Chelsea soil humic acid[J]. Environ. Sci. Technol. 2003, 37: 1783-1793.
Feng J & Moller D. Characterization of water-soluble macromolecular substances in cloud water[J]. J Atmos Chem, 2004,48:217-233.
Green S A, Blough N V. Optical absorption and fluorescence properties of chromophoric dissolved organic matter in natural waters[J]. Limnol Oceanogr, 1994, 38:1 903-1 916.
Kieber R J, Hardison D R, Whitehead R F, et al. Photochemical production of Fe(II) in rainwater[J]. Environ. Sci. Technol. 2003, 37:4610-4616.
Kieber R J, Skrabal S A, Smith B, et al. Organic complexation of Fe(II) and its impact on the redox cycling of iron in rain[J]. Environ. Sci. Technol. 2005, 39:1576-1583.
Kieber R J, Skrabal S A, Smith B, et al. Redox speciation of copper in rainwater: Temporal variability and atmospheric deposition[J]. Environ. Sci. Technol. 2004, 38: 3587-3594.
Kieber R J, Whitehead R F, Reid S N, et al. Chromophoric dissolved organic matter (CDOM) in rainwater, Southeastern North Carolina, USA[J]. Journal of Atmospheric Chemistry .2006,54:21-41.
Kieber R J, Willey J D, Zvalaren S D. Chromium speciation in rainwater: Temporal variability and atmospheric deposition[J]. Environ Sci Technol, 2002, 36:5321-5327.
McKnight D M, Boyer E W, Westerhoff P K, et al. Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity[J]. Limnol Oceanogr, 2001, 46(1): 38-48.
Witt M L I, Skrabal S, Kieber R, et al. Photochemistry of Cu complexed with chromophoric dissolved organic matter: implications for Cu speciation in rainwater[J]. J Atmos Chem, DOI 10.1007/s10874-007-9079-5.
Zepp R G. Solar Ultraviolet Radiation And Aquatic Carbon, Nitrogen, Sulfur And Metals Cycles[A]. In: UV Effects In Aquatic Organisms And Ecosystems[C], E.W.Helbling & H. Zagarese (eds), Royal Society of Chemistry, Cambridge UK, 2002, pp. 137-183.