autumn photoproduction of carbon monoxide in jiaozhou bay, china

J. Ocean Univ. China (Oceanic and Coastal Sea Research) DOI 10.1007/s11802-014-2225-1 ISSN 1672-5182, 2014 13 (3): 428-436 http://www.ouc.edu.cn/xbywb/ E-mail:[email protected]

Autumn Photoproduction of Carbon Monoxide in Jiaozhou Bay, China

REN Chunyan1, 2), YANG Guipeng1), *, and LU Xiaolan1)

1) Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, P. R. China

2) College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao 266109, P. R. China

(Received December 16, 2012; revised March 3, 2013; accepted May 18, 2013) © Ocean University of China, Science Press and Springer-Verlag Berlin Heidelberg 2014

Abstract Carbon monoxide (CO) plays a significant role in global warming and atmospheric chemistry. Global oceans are net natural sources of atmospheric CO. CO at surface ocean is primarily produced from the photochemical degradation of chromophoric dissolved organic matter (CDOM). In this study, the effects of photobleaching, temperature and the origin (terrestrial or marine) of CDOM on the apparent quantum yields (AQY) of CO were studied for seawater samples collected from Jiaozhou Bay. Our results demonstrat that photobleaching, temperature and the origin of CDOM strongly affected the efficiency of CO photoproduction. The concentration, absorbance and fluorescence of CDOM exponentially decreased with increasing light dose. Terrestrial riverine organic matter could be more prone to photodegradation than the marine algae-derived one. The relationships between CO AQY and the dis-solved organic carbon-specific absorption coefficient at 254 nm for the photobleaching study were nonlinear, whereas those of the original samples were strongly linear. This suggests that: 1) terrestrial riverine CDOM was more efficient than marine algae-derived CDOM for CO photoproduction; 2) aromatic and olefinic moieties of the CDOM pool were affected more strongly by degradation processes than by aliphatic ones. Water temperature and the origin of CDOM strongly affected the efficiency of CO photoproduction. The photoproduction rate of CO in autumn was estimated to be 31.98 μmol m−2

d−1 and the total DOC photomineralization was equivalent to 3.25% 6.35% of primary production in Jiaozhou Bay. Our results indicate that CO photochemistry in coastal areas is important for oceanic carbon cycle.

Key words carbon monoxide; photoproduction; apparent quantum yield; photobleaching; CDOM

1 Introduction As the second largest product of chromophoric dis-

solved organic matter (CDOM) photolysis, carbon mon-oxide (CO) in surface seawater has been broadly ob-served over the last several decades (Conrad et al., 1982; Mopper et al., 1991; Zafiriou et al., 2003; Stubbins et al., 2006). CO is primarily produced from CDOM photolysis (Zuo et al., 1995; Zafiriou et al., 2003) and lost to micro-bial processes (Zafiriou et al., 2003; Xie et al., 2005), sea-to-air gas exchange (Conrad et al., 1982; Stubbins et al., 2006) and vertical mixing (Johnson and Bates, 1996; Kettle, 2005). These chemical, biological and physical interactions lead to complex spatial and temporal distributions of sea surface CO. CO is also a key proxy to evaluate the photoproduction of dissolved inorganic car-bon (DIC), biolabile carbon and nitrogen compounds be-cause of their difficulty to measure (Miller, 1995, 2002; Mopper, 2000). CO apparent quantum yield (AQY) data

* Corresponding author. Tel: 0086-532-66782657

E-mail: [email protected]

have been reported for a number of samples including those from high carbon waters (Zhang and Xie, 2011; Yang et al., 2011; Gao and Zepp, 1998; Valentine and Zepp, 1993), sea ice (Song et al., 2011) and open-ocean waters (Zafiriou et al., 2003; Stubbins et al., 2006). The AQY spectra reported on near-coastal waters were higher than those on Sargasso Sea waters and blue waters, sug-gesting that terrestrial CDOM might exhibit different ef-ficiency and be more efficient at producing CO than ma-rine CDOM. However, there are still many gaps in our understanding of the influencing factors on CO produc-tion and the coastal photoproduction of CO. In this study, we collected several different water samples from Jiao- zhou Bay, China to examine the factors controlling CO photoproduction, such as photobleaching and temperature. Furthermore, the total amount of CO photoproduction in Jiaozhou Bay in autumn was calculated.

2 Materials and Methods 2.1 Study Area

Jiaozhou Bay is the largest semi-enclosed bay on the western part of the Shandong Peninsula, China (Fig.1).

REN et al. / J. Ocean Univ. China (Oceanic and Coastal Sea Research) 2014 13: 428-436

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Fig.1 Locations of the sampling stations in Jiaozhou Bay, China.

The bay is surrounded by the city of Qingdao with an area of about 390 km2 and a mean water depth of about 7 m. The bay mouth is narrow, only about 2.5 km wide and connects with the South Yellow Sea. The water exchange rate between the bay and the open sea is high, being 7%, and the half of exchange period is 5 d (Liu, 1992). More than 10 small rivers enter the bay, the largest being Dagu River and the rest including Haipo River, Licun River, Loushan River and so on. Most of these rivers pass through the urban areas of Qingdao, which causes Jiaozhou Bay greatly influenced by human activities, such as wastewater discharge from domestic, industrial, agricultural and marine-cultural activities (Shen, 2001).

2.2 Sample Collection and Pretreatment

Cruise was conducted in Jiaozhou Bay on November 11, 2008, and the sampling locations are shown in Fig.1. At each location, surface seawater samples (2 m deep) were collected using 12 L Niskin bottles. After collection, samples were filtered through 0.45 μm and 0.2 μm poly-ethersulfone membranes (Pall, USA). The filtered water was transferred in the dark into acid-cleaned clear glass bottles, stored in darkness at 4℃, and brought back to the laboratory. Samples were re-filtered with 0.2 μm polyeth-ersulfone membranes (Pall, USA) immediately before irradiation.

The filtered water samples, placed in clean glass bottles covered with a quartz plate, kept at 15℃, were irradiated with a SUNTEST CPS solar simulator (Atlas, Germany) equipped with a Xelon lamp. The output of the Xe-lamp was adjusted to 765 W m−2 and determined with an ILT- 900R UV-VIS spectroradiometer (International Light Technologies, USA). Irradiation times varied from 4 h to 240 h to obtain various photobleaching degree samples, whose contents of dissolved organic matter (DOM) were all different from that of the original samples.

2.3 Analytical Methods

Before irradiation, water samples were stripped with

CO-free air to decrease CO concentration of the samples and then determined for the determination of the initial concentration. Then seawater samples were transferred into gastight quartz cells and placed into the SUNTEST CPS solar simulator to be irradiated with the temperature of water-bath controlled at 15℃. The SUNTEST CPS solar simulator was modified with eight long-pass cut-off filters (280, 295, 305, 320, 345, 395, 435 and 495 nm, numbers being nominal 50% transmission cutoff wave-length) to obtain different solar wave bands and deter-mined with an ILT-900R UV-VIS spectroradiometer. Right after irradiation, water samples were transferred into 50 mL glass acid-cleaned syringes fitted with three- way Nylon valves and analyzed with TA 3000 gas ana-lyzer (Ametek, USA) (Lu et al., 2010). CO concentration (CCO) was calculated according to Xie et al. (2002).

Absorbance spectra were measured from 200 to 800 nm at 1 nm increment in quartz cell against Milli-Q water reference using an UV-2550 UV-VIS spectrometer (Shi-madzu). A baseline correction was applied by subtracting the absorbance value which was an average over a 5-nm interval around 685 nm from all the spectral values (Babin et al., 2003). This spectral range around 685 nm was chosen because of the negligible CDOM absorption and the very small temperature and salinity effects on water absorption (Pegau et al., 1997). Then absorption coeffi-cients (a) (m−1) were calculated as (Loh et al., 2004):

2.303 Aa

L

,

where A is the absorbance, and L is the path length (m). Dissolved organic carbon (DOC) was measured using a

TOC-5000A carbon analyzer (Shimadzu) calibrated with potassium biphthalate. The relative standard deviation was less than 2%.

Excitation-Emission Matrix Spectra (EEMs) of the or-ganic matter was measured in 1-cm quartz cell against Milli-Q water reference using F-4500 fluorescent spec-trometer (Hitachi). The excitation and emission ranges were both from 200 to 500 nm and the increments were both 5 nm.

Apparent quantum yield (AQY(λ)) is traditionally de-fined as the ratio of the number of molecules transformed via one reaction pathway to the number of photons ab-sorbed by the reactant at a given wavelength. So AQY was here defined as follows:

3 1

λ

2 1 1

CO produced (moles m s )AQY

Photons absorbed by CDOM in

sample (moles m s nm )

- -

-

.

A Matlab-coded iterative curve-fit method was em-ployed to derive AQY(λ) (Johannessen and Miller, 2001). Zhang’s (2006) recommendation was adopted to calculate AQY as follows:

21

3

AQY λ exp( )λ

mm

m

,

where m1, m2 and m3 are fitting parameters. This function


430

has been demonstrated to perform generally better (Xie and Gosselin, 2005).

CO production rate in the irradiation cell could be pre-dicted by the equation below:

6001

280P ( ) ( )di abL AQY Q

where Qab(λ) is photons absorbed by CDOM at a specific wavelength.

Then χ2 error could be calculated as:

82 2

1

[log[ ] log( )]i ii

P P

where Pi is the measured CO production rate. The fit pa-rameters (m1, m2 and m3) were derived by changing them iteratively from their initial estimates until the χ2 error was minimized.

3 Results and Discussion 3.1 Influence of Light Dose on the Contents of

CDOM

There are 7 types of peaks of fluorescent DOM in sea-water, and the major 3 types and their peak positions are listed in Table 1. Peaks A, S and T are humic-like and protein-like peaks, which are the primary components of CDOM (Coble, 1996; Parlanti et al., 2000). Several or-ganic compound EEMs of different photobleaching de-grees for Licun estuary samples are shown in Fig.2. Peak A can be clearly observed at Ex/Em being 250/470 nm of

non-photobleached sample (photobleaching time is zero), whose fluorescent value is very high and covers up peak S at 235/370 nm and peak T at 280/350 nm on the whole. After some period of photobleaching, peak S and peak T were very obvious with the disappearing of peak A in other EEMs. At the same time, emission wavelengths of peak S and peak T decreased from 370 nm to 355 nm and from 350 nm to 325 nm, respectively, but excitation wavelength remained the same. The fluorescent values of peaks A, S and T were significantly decreased with the photobleaching time. After the long time of photobleach-ing (236 h), humic-like substances were mostly degraded (the fluorescent value of peak A was only 7.56% of the original value), but a large amount of protein-like sub-stances remained (the fluorescent values of peak S and peak T were 37.87% and 55.02% of the original value, respectively). It has been reported that humic substances could mostly be photodegraded by sunlight into a variety of photoproducts including low-molecular-weight organic compounds, which could be separated into three main categories: 1) aliphatic mono-and dibasic acids; 2) keto-acids; 3) aromatic hydroxy carboxylic acids and alde-hydes (Kieber and Mopper, 1987; Kieber et al., 1990; Wetzel et al., 1995; Nina Corin et al., 1996) and inor-ganic compounds such as CO, DIC and carbonyl sulfide (COS), but the degradation of protein-like substances was much smaller (Andreae and Ferek, 1992; Miller and Zepp, 1995; Moran and Zepp, 1997). Our investigations testi-fied this point.

Absorption coefficient at 350 nm (a350) and the fluo-rescent value of peak A (IF(A)) are the proxy of the con-

Fig.2 EEMs of different photobleaching degrees in the samples from B5 station (photobleaching times are 0, 4, 64, 120, 173 and 236 h, respectively).


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Table 1 Major fluorescent types of dissolved organic matter in seawater

Peak Ex/Em (nm) Peak couple

A 230 260/400 460 Humic-like S 225 235/330 350 Tryptophan-like of high excitation wavelength T 265 280/330 350 Tryptophan-like of low excitation wavelength

tent of CDOM, to some extent, because these optical pa-rameters are directly related to the concentration and photoreactivity of DOM (Zuo and Jones, 1997). The in-fluence of light dose on a350 and IF(A) in the photo-bleaching of CDOM were investigated.

The influence of light dose on a350 and fluorescent peak A are shown in Fig.3. It can be seen from Fig.3 that both a350 and IF(A) exponentially decreased with the increasing light dose in all 5 different samples. During the first 4 hours of photobleaching, both a350 and IF(A) sharply de-clined. Thereafter, a350 and IF(A) decreased slowly. Dur-ing long time photobleaching, a350 and IF(A) remained approximately constant. This suggests that a significant

amount of the DOM, especially more hydrophilic moie-ties of the DOM, was degraded at the beginning of photobleaching, and the residual organic matter after long time photobleaching should be some refractory organic substances (Brinkmann et al., 2003).

Among different samples, the extents of degredation were different. During long time photobleaching, most of the organic matter was degraded in the samples from B5, D4 and B1 stations. However, quite a number of organic matters remained in the water after long time photo-bleaching with samples from C3 and E3. This was mainly due to their different sources of CDOM. Terrestrial or-ganic matter has a greater aromaticity than marine DOM

Fig.3 The influence of light dose on a350 and fluorescent peak A.


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and may be more prone to photodegradation, so most of them could be degraded after long time photobleaching as discussed by Moran and Hodson (1994). In contrast, the pool of marine algae-derived DOM was relatively resis-tant against natural UV radiation and not so readily photo-oxidized (Thomas and Lara, 1995). For samples from B5, D4 and B1 stations (Fig.4), almost all organic matter was from terrestrial riverine import, so most of them could be degraded. For samples from C3 and E3 stations, most of the organic matter was of marine origin and only a small part was of terrestrial origin, so there were still many organic compounds left during long time photobleaching (Zhang et al., 2002).

Fig.4 The relationship between CO AQY and water tem-perature of B5 and D4 samples.

3.2 Temperature Dependence

To assess the effect of temperature on CO photopro-duction, the original samples from B5 and D4 were irra-diated at four temperatures: 5, 10, 15 and 20℃, and the AQY–temperature relationship is shown in Fig.5. We can see that the relationship followed the linear Arrehenius behavior. The activation energy for samples from stations B5 and D4 were 19.15 and 13.59 kJ mol−1, respectively, bo th be ing smal ler than 20 kJ mol− 1 . For an

Fig.5 Effects of photobleaching on the CO AQY as illus-trated by f330.

increase per 10 K, the AQY increased by about 35% and 22%, respectively, which are accordant with Zhang (2006), but much lower than van’t Hoff rule’s coefficient. However, the temperature dependence of AQY demon-strated that secondary photoreactions were involved in the CO production. This viewpoint is supported by the fact that aromatics without the carbonyl group are the domi-nant CO precursors (Hubbard, 2006). However, the pos-sibility of CO production through primary photoreaction may still exist. That is mainly because some simple car-bonyl compounds such as formaldehyde and acetaldehyde can be produced by photoreaction in natural seawater (Kieber, 1990) and decomposed to CO by the solar UV spectrum.

3.3 Photobleaching Dependence

The wavelength peak of CO production is about 330 nm, so the fraction of the original a330 (f330) was chosen to describe the photoleaching degree of water samples (Zhang et al., 2006). The dependence of AQY on CDOM photobleaching is depicted as plots of AQY vs f330 (Fig.5). The dose dependence varied widely among different samples and at different stages of photobleaching. AQY for estuary samples (stations B5, D4 and B1) decreased dramatically at first, continued to decline thereafter at gradually reducing rates, and eventually became ap-proximately constant. Station C3 in the bay center and station E3 in the bay mouth exhibited a similar pattern, but the initial decrease in AQY was much smaller.

The dissolved organic carbon-specific absorption coef-ficient at 254 nm (SUVA254, defined as a254 divided by DOC, with a unit of L m−1 (mg C) −1) was an indicator of the aromatic carbon content of DOM (Weishaar et al., 2003). The dependence of AQY on SUVA254 was also examined (Fig.6). Similar to the AQY vs f330 pattern, the AQY-SUVA254 relationship observed for the photo-bleaching study was nonlinear, which was different from strong linear correlation found for the original samples (Fig.7). At the beginning of photobleaching, AQY de-creased sharply in the B5, D4 and B1 samples, which represented the conditions of Licun estuary, Haipo estu-ary and Dagu estuary, respectively. In contrast to these three sets of samples, AQY also decreased but not so sharply in the samples from C3 (the bay center) and E3 (the bay mouth). However, SUVA254 did not decline rap-idly like AQY, suggesting that reactive CO precursors contained aromatic moieties, but the aromatic rings were not destroyed during the initial process (Zhang et al., 2006). Thereafter, the AQY decreased slowly with the decrease of SUVA254. During more than 120 hours’ photo-bleaching, AQY eventually became relatively constant, but SUVA254 continued to decline. These observations showed that: 1) there should be two classes of CO pro-ducers: terrestrial riverine CDOM and marine algae- de-rived CDOM, terrestrial CDOM being more reactive than the other in the photoproduction of CO; 2) Aromatic and olefinic moieties of the CDOM pool were affected more strongly by degradation processes than by aliphatic ones


433

(Mopper and Kieber, 2000).

Fig.6 Effects of photobleaching on the CO AQY as illus-trated by SUVA254.

Fig.7 The relationship between AQY and SUVA254 of the original samples.

3.4 CO Photoproduction

AQYs were significantly correlated with SUVA254 of all original samples (Fig.7), suggesting that aromatic and olefinic moieties of the CDOM pool strongly affected AQY relative to aliphatic ones. Stubbins (2008) has demonstrated that many specific aromatic compounds are efficient CO producers. As terrestrial DOM (samples such as those from B5 and D4 stations) usually contain more aromatic compounds than marine algae-derived one (samples such as the others) (see Table 2), AQYs of the former two samples were much higher than those of the others.

AQY spectra for CO photoproduction are presented in Fig.8. By comparison, the AQY spectrum of the samples collected from station B5 was significantly higher in magnitude, indicating that CO was produced with a much higher photochemical efficiency in the sample compared with the other samples from the bay. This higher effi-ciency was likely due to the higher value of SUVA254 (Table 2). Since no statistical difference was observed in the photochemical efficiency of CDOM to produce CO for stations throughout the bay (most of the three fitting parameters (m1, m2 and m3) were close in value), a pooled AQY spectrum was calculated by applying a single ex-ponential fit to all CO production.

The pooled AQY spectra of Jiaozhou Bay samples, to-gether with the average freshwater (Valentine and Zepp, 1993), and for the East China Sea (ECS) and the Yellow Sea (YS) (Yang et al., 2011) and average Pacific blue water (Zafiriou et al., 2003), are displayed in Fig.8. Across the whole UV-visible regimes, the AQY of fresh-water was the highest, those of Jiaozhou Bay and the ECS and YS samples were intermediate, and the blue water had the lowest value. This indicates that the contribution of continental shelves and coastal regions to the global oceanic photoproduction of CO might not be neglected. However, the differences of these AQY values diminished with decreasing wavelength. As the samples from station B5 had lower salinity (S = 23.451) and thus contained

Fig.8 Comparison of AQY spectra for Jiaozhou Bay in this study with previously published AQY spectra. The AQY spectrum for average freshwater is from Valentine and Zepp (1993), the ECS and YS from Yang et al. (2011) and those for average Pacific blue water from Zafiriou et al. (2003).

Table 2 Physical and chemical parameters of the water samples

Subjects Station Temperature (℃) Salinity

SUVA254 L m−1 (mg C)−1 AQY Photobleaching series Temperature series

B1 13.2 30.241 4.47 ★ ★ B3 14.4 30.089 2.81 ★ B5 12.0 23.451 6.44 ★ ★ ★ C1 10.8 29.761 4.10 ★ C3 13.6 30.288 3.21 ★ ★ D1 13.1 29.392 3.65 ★ D3 ud 30.012 2.35 ★ D4 10.0 29.877 6.22 ★ ★ ★ E3 15.6 30.458 3.23 ★ ★


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more terrestrial CDOM (SUVA254 = 6.44 L m−1 (mg C) −1) than those from station E3, the CO spectrum with station B5 was much closer to that with freshwater area. These observations suggest that the two precursors of CDOM (terrestrial and marine derived CDOM) had different effi-ciencies to produce CO and the terrestrial CDOM was more prone to photolysis than the marine algae-derived one. Our result also showed the presence of multiple CO precursors that were less selectively photolyzed by UV-B radiation than by UV-A and visible radiations.

CO photoproduction rates over all the relevant wave-length range (280 600 nm) were calculated as (Zafiriou et al., 2003; Xie et al., 2009):

1 2600

CDOM280COOcean area

Total

dAQY

Irradiance Attenuation factor

,

where irradiance is global spectral solar irradiance; at-tenuation factors 1 is correction for the reflection of light by clouds, derived from UV reflectivity (Eck et al., 1995), the average value in Jiaozhou Bay in autumn being 0.70; attenuation factors 2 is the transmittance at the air-sea interface, the value being about 0.94, a mean of all of the Fresnel reflectivity (Liu, 2009); αCDOM and αTotal are the CDOM and the sum of the absorption coefficients of CDOM, particles and seawater in the water column; AQYCO is the AQY of CO at each wavelength between 280 and 600 nm.

The Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS2 model) (Gueymard, 2001), which covers a full range of photochemically ac-tive radiation (280 4000 nm) and with a spectral resolu-tion of at least 0.5 nm, was used to calculate the CO pho-toproduction rates. This model has been validated over the North Atlantic Ocean by Stubbins et al. (2006), who found that the model could accurately and precisely pre-dict variations of irradiance between 280 450 nm; but above 450 nm, the model overestimated irradiance by about 10%. Using SMARTS2 irradiance and the CDOM- based AQYCO spectrum as described above, the CO pho-toproduction rate in Jiaozhou Bay in autumn was calcu-lated to be 31.98 μmol m−2

d−1.

3.5 Implications for Coastal Carbon Cycle

CO is the second abundant inorganic carbon product after DIC, whose photoproductive amount can be used to estimate the total photomineralization of DOC. Using the ratios of DIC to CO photoproduction of 1020 (Day and Faloona, 2009; White et al., 2010) and the ratio of DIC photoproduction to the photochemical release of biolabile organic carbon of approximately 1 (Miller et al., 2002), the total photomineralization of DOC in Jiaozhou Bay was estimated to be 8.06 15.73 mg C m−2

d−1. Assuming the primary production of the bay in autumn to be 247.81 mg C m−2

d−1 (Sun et al., 1995), DOC photomineralization is equivalent to 3.25%6.35% of primary production in Jiaozhou Bay. This estimate is higher than the previous

estimate of photochemical DOC mineralization in the coastal area of the northern California upwelling system (2.5%; Day and Faloona, 2009). Our result provides the evidence that the photolytic mineralization of dissolved organic matter should be regarded as a noteworthy com-ponent of the regional carbon cycle in the Jiaozhou Bay ecosystem.

4 Conclusion Our findings have several implications for assessing

the importance of photochemical formation of CO and carbon cycling in sea water. First, our study demonstrates that DOM, especially humic-like substances, could be significantly degraded by long time photobleaching in surface seawater, which could further affect the cycling of carbon and other reactive elements in marine ecosystems. Second, our results strongly suggest that long time photo-bleaching could significantly influence the photoproduc-tion of CO, especially in near-coastal and continental shelf areas whose organic matters are mostly from terres-trial riverine origin. Finally, based on the CO photopro-duction rate calculated for Jiaozhou Bay, the total DOC photomineralization is estimated to be 8.0615.73 mg C m−2

d−1, equivalent to 3.25%6.35% of primary produc-tion in Jiaozhou Bay. This result suggests that photo-chemistry of CO may be an important component in the carbon cycling of this studied system. Further studies should be designated to identify the seasonal variation of CO photoproduction and pay more attention to coastal areas to evaluate the global total CO photoproduction.

Acknowledgements This work was financially supported by the National

Natural Science Foundation of China (No. 40976043), the Science and Technology Key Project of Shandong Prov-ince (2006GG2205024), the Changjiang Scholars Pro-gram, Ministry of Education of China, the Taishan Schol-ars Program of Shandong Province, and the Scholar Foundation of Qingdao Agricultural University (631102).

References Andreae, M. O., and Ferek., R. J., 1992. Photochemical produc-

tion of carbonyl sulfide in seawater and its emission to the atmosphere. Global Biogeochemical Cycles, 6: 175-183.

Babin, M., Stramski, D., Ferrari, G. M., Claustre, H., Bricaud, A., Obolensky, G., and Hoepffner, N., 2003. Variations in the light absorption coefficients of phytoplankton, nonalgal parti-cles and dissolved organic matter in coastal waters around Europe. Journal of Geophysical Research, 108 (C7), DOI 10.1029/2001jc000882.

Brinkmann, T., Horsch, P., Sartorius, D., and Frimmel., F. H., 2003. Photoformation of low-molecular-weight organic acids from brown water dissolved organic matter. Environmental Science and Technology, 37: 4190-4198.

Coble, P. G., 1996. Characterization of marine and terrestrial DOM in seawater using excitation-emission matrix spectros-copy. Marine Chemistry, 51: 325-346.


435

Conrad, R., Seiler, W., Bunse, G., and Giehl, H., 1982. Carbon Monoxide in seawater (Atlantic Ocean). Journal of Geo-physical Research, 87 (C11): 8839-8852.

Corin, N., Backlund, P., and Kulovaara, M., 1996. Degradation products formed during UV-irradiation of humic waters. Chemosphere, 33 (2): 245-255.

Day, D. A., and Faloona, I., 2009. Carbon monoxide and chro-mophoric dissolved organic matter cycles in the shelf waters of the northern California upwelling system. Journal of Geo-physical Research, 114 (C01006), DOI: 10.1029/2007JC004 590.

Eck, T. F., Bhartia, P. K., and Kerr, J. B., 1995. Satellite estima-tion of spectral UVB irradiance using TOMS derived total ozone and UV reflectivity, Geophysical Research Letters, 22: 611-614.

Gao, H., and Zepp, R. G., 1998. Factors influencing photoreac-tions of dissolved organic matter in a coastal river of the southeastern United States. Environmental Science and Tech-nology, 32: 2940-2946.

Johnson, J. E., and Bates, T. S., 1996. Sources and sinks of car-bon monoxide in the mixed layer of tropical South Pacific Ocean. Global Biogeochemical Cycles, 10 (2): 347-359.

Kettle, A. J., 2005. Diurnal cycling of carbon monoxide (CO) in the upper ocean near Bermuda. Ocean Modelling, 8: 337-367.

Kieber, D. J., and Mopper., K., 1987. Photochemical formation of glyoxylic and pyruvic acids in seawater. Marine Chemistry, 21: 135-149.

Kieber, D. J., McDaniel, J., and Mopper, K., 1989. Photo-chemical source of biological substrates in sea water: Impli-cations for carbon cycling. Nature, 341: 637-639.

Kieber, D. J., Zhou, X., and Mopper, K., 1990. Formation of carbonyl compounds from UV-induced photodegradation of humic substances in natural waters: Fates of riverine carbon in the sea. Limnology and Oceanography, 35: 1503-1515.

Liu, R. Y., 1992. Characteristics of physical environmental of Jiaozhou Bay. Ecology and Biological Resources of Jiaozhou Bay. Science Press, Beijing, 25-30 (in Chinese).

Liu, Y. G., 2009. Satellite Oceanography. Higher Education Press, Beijing, 171pp.

Loh, A. N., Bayer, J. E., and Druffel, E. R. M., 2004. Variable ageing and storage of dissolved organic components in the open ocean. Nature, 430: 877-881.

Lu, X. L., Yang, G. P., Wang, X. M., Wang, W. L., and Ren, C. Y., 2010. Determination of carbon monoxide in seawater by headspace analysis. Chinese Journal of Analytical Chemiatry, 38 (3): 352-356, DOI: 10.3724/SP.J.1096.2010.00352.

Miller, W. L., Moran, M. A., Sheldon, W. M., Zepp, R. G., and Opsahl, S., 2002. Determination of apparent quantum yield spectra for the formation of biologically labile photoproducts. Limnology and Oceanography, 47: 343-352.

Miller, W. L., and Zepp, R. G., 1995. Photochemical production of dissolved inorganic carbon from terrestrial organic-matters significance to the oceanic organic-carbon cycle. Geophysical Research Letters, 22: 417-420.

Mopper, K., and Kieber, D. J., 2000. Marine Photochemistry and its Impact on Carbon Cycling. The Effects of UV Radia-tion in the Marine Environment. Cambridge University Press, Cambridge, 101-129.

Mopper, K., Zhou, X. L., Kieber, R. J., Sikorski, D. J., and Jones, R. D., 1991. Photochemical degradation of dissolved organic carbon and its impact on the oceanic carbon cycle. Nature, 353 (6339): 60-62.

Moran, M. A., and Hodson, R. E., 1994. Support of bacterio-plankton production by dissolved humic substances from

three marine environments. Marine Ecology Progress Series, 110: 241-247.

Moran, M., and Zepp, R., 1997. Role of photoreactions in the formation of biologically labile compounds from dissolved organic matter. Limnology and Oceanography, 42 (6): 1307- 1316.

Nelson, N. B., Siegel, D. A., and Michaels, A. F., 1998. Sea-sonal dynamics of colored dissolved organic material in the Sargasso Sea. Deep-Sea Research I, 45 (6): 931-957.

Parlanti, P., Worz, K., Geoffroy, L., and Lamotte, M., 2000. Dissolved organic matter fluorescence spectroscopy as a tool of estimate biological activity in a coastal zone submitted to anthropogenic inputs. Organic Geochemistry, 31: 1765-1781.

Pegau, W. S., Deric, G., and Zaneveld, J. R. V., 1997. Absorp-tion and attenuation of visible and near-infrared light in water: Dependence on temperature and salinity. Applied Optics, 36 (24): 6035-6046.

Shen, Z. L., 2001. Historical changes in nutrient structure and its influence on phytoplankton composition in Jiaozhou Bay. Estuarine, Coastal and Shelf Science, 52: 211-224.

Song, G., Xie, H., Aubry, C., Zhang, Y., Gosselin, M., Mundy, C. J., Philippe, B., and Papakyriakou, T. N., 2011. Spatiotempo-ral variations of dissolved organic carbon and carbon monox-ide in first-year sea ice in the western Canadian Arctic. Jour-nal of Geophysical Research, 116 (C00G05), DOI: 10.1029/ 2010JC 006867.

Stubbins, A., Uher, G., Law, C. S., Mopper, K., Robinson, C., and Upstill-Goddard, R. C., 2006. Open-ocean carbon mon-oxide. Deep-sea Research II, 53: 1695-1705.

Stubbins, A., Hubbard, V., Uher, G., Law, C. S., Upstill-Goddard, R. C., Aiken, G. R., and Mopper, K., 2008. Relating carbon monoxide photoproduction to dissolved organic matter func-tionality. Environmental Science and Technology, 42: 3271- 3276.

Thomas, D. N., and Lara, R. J., 1995. Photodegradation of algal derived dissolved organic carbon. Marine Ecology Progress Series, 116: 309-310.

Valentine, R. L., and Zepp, R. G., 1993. Formation of carbon monoxide from the photodegradation of terrestrial dissolved organic carbon in natural waters. Environmental Science and Technology, 27 (2): 409-412.

Wetzel, R. G., Hatcher, P. G., and Bianchi, T. S., 1995. Natural photolysis by ultraviolet irradiance of recalcitrant dissolved organic matter to simple substrates for rapid bacterial me-tabolism. Limnology and Oceanography, 40: 1369-1380.

White, E. M., Kieber, D. J., Sherrard, J., Miller, W. L., and Mopper, K., 2010. Carbon dioxide and carbon monoxide pho-toproduction quantum yields in the Delaware Estuary. Marine Chemistry, 118: 11-21.

Wiesenburg, D. A., and Guinasso, N. L., 1979. Equilibrium solubilities of methane, carbon monoxide, and hydrogen in water and sea water. Journal of Chemical and Engineering Data, 24: 356-360.

Xie, H., Andrews, S. S., Martin, W. R., Miller, J., Ziolkowski, L., Taylor, C. D., and Zafiriou, O. C., 2002. Validated meth-ods for sampling and headspace analysis of carbon monoxide in seawater. Marine Chemistry, 77: 93-108.

Xie, H., Zafiriou, O. C., Umile, T. P., and Kieber, J., 2005. Bio-logical consumption of carbon monoxide in Delaware Bay, NW Atlantic and Beaufort Sea. Marine Ecology Progress Se-ries, 290: 1-14.

Xie, H., Belanger, S., Demers, S., and Papakyriakou, T. N., 2009. Photobiogeochemical cycling of carbon monoxide in the southeastern Beaufort Sea in spring and autumn. Limnol-


436

ogy and Oceanography, 54 (1): 234-249. Yang, G. P., Ren, C. Y., Lu, X. L., Liu, C. Y., and Ding, H. B.,

2011. Distribution, flux and photoproduction of carbon mon-oxide in the East China Sea and the Yellow Sea in spring. Journal of Geophysical Research, 116 (C02001), DOI: 10. 1029/2010JC 006300.

Zafiriou, O. C., Andrews, S. S., and Wang, W., 2003. Concor-dant estimates of oceanic carbon monoxide source and sink processes in the Pacific yield a balanced global ‘blue-water’ CO budget. Global Biogeochemical Cycles, 17 (1): 1015, DOI: 10.1029/2001gb001638.

Zepp, R. G., and Cline, D. M., 1977. Rates of direct photolysis in aquatic environments. Environmental Science and Tech-nology, 11: 359-366.

Zhang, X. Q., Wu, Y. S., Zhang, S. K., and Wu, L. Y., 2002. The distribution on fluorescence intensity of yellow substance in

Jiaozhou Bay. Journal of Remote Sensing, 6 (3): 229-232. Zhang, Y., and Xie, H., 2011. The sources and sinks of carbon

monoxide in the St. Lawrence estuarine system. Deep-Sea Research II, DOI:10.1016/j.dsr2.2011.09.003.

Zhang, Y., Xie, H., and Chen, G. H., 2006. Factors affecting the efficiency of carbon monoxide photoproduction in the St. Lawrence estuarine system (Canada). Environmental Science and Technology, 40: 7771-7777.

Zuo, Y., and Jones, R. D., 1995. Formation of carbon monoxide by photolysis of dissolved marine organic material and its significance in the carbon cycling of the ocean. Naturwissen-schaften, 82 (10): 472-474.

Zuo, Y., and Jones, R. D., 1997. Photochemistry of natural dis-solved organic matter in lake and wetland waters-production of carbon monoxide. Water Research, 31 (4): 850-858.

(Edited by Ji Dechun)

autumn photoproduction of carbon monoxide in jiaozhou bay, china

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