YU Zhigang1, YAO Peng1, YAO Qingzhen2 and MI Tiezhu3
1. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266003, China
2. College of Fisheries, Shanghai Fisheries University, Shanghai 200090, China
3. College of Environmental Science and Engineering, Ocean University of China, Qingdao 266003, Chin
The advancement in marine biogeochemistry studies in China from 1998 until 2002 is reviewed in this paper. The major research results and latest advancement are summarized in six aspects: biogenic elements in estuarine and coastal areas, heavy metals, isotope, organic pollutants, organic geochemistry and greenhouse gases.
Key words: Marine biogeochemistry, Biogenic element, Isotope, Heavy metal, Organic Pollutant, Organic geochemistry, Greenhouse gas
Biogeochemistry is the science which studies the relationship between organism and its environment through tracing the transport and transform of chemical elements. Marine biogeochemistry is such a science that it introduces the concept and research approach of biogeochemistry into the research field of marine sciences. It is an intersected discipline emerged by the infiltration of chemical oceanography, marine geology and marine biology. It mainly focuses on the geo-chemical process involved in by marine organism and on the effect of marine geo-chemical environment on marine organism to reveal the correlation of element composition of marine organism and its environment. The formation of marine biogeochemistry is the consequence of increasing synthesis of marine sciences and extension of multi-discipline intersection. It is also caused by increasing attention paid by human society to the research of geosphere-biosphere interaction and global change. Marine biogeochemistry has been one of the most active frontiers of marine sciences in the recent two or three decades. Marine biogeochemistry study performs important functions in the research of important scientific problems such as the ocean fluxes in the China Sea and its adjacent sea area, the shallow sea ecosystem dynamics, the land-ocean interaction of coastal zone and the red tide process dynamics.
Chinese marine biogeochemistry studies began at the end of the 1970s. By and large, they can be divided into three stages. the first stage is from the end of 1970s to the end of 1980s, i.e. the first decade, when several international cooperative projects had been carried out such as the Sino-America joint investigation starting from 1980, the Sino-America and Sino-France Yellow River Estuary investigation starting from 1985 and the Sino-France Yangtze River Estuary biogeochemical investigation in pollutants and nutrient elements. In this stage Chinese scientists widely kept abrest of the newest technologies and methods of marine biogeochemistry research abroad. It not only greatly promoted the research into Chinese estuarine chemistry and marine biogeochemistry, but also fostered a large number of young academic heads who have been active in the first-line work of Chinese marine science research, which built up a sound foundation in the development of Chinese marine biogeochemistry research. The second stage is from the end of 1980s to the end of 1990s, i.e. the second decade. Chinese marine biogeochemistry research had been greatly developed in this decade, and some important frontier subjects were made independently, for example, the NSFC key projects “Studies on Ocean Flux of the East China Sea Shelf Margin”(1992-1995), “Studies on Key Process of the East China Sea Ocean Fluxes”(1996-1999) and “Studies on Biogeochemical Process of Bio-genic elements in the Taiwan Strait”(1997-2000). The rich achievements in biogeochemistry have been obtained and a research system with Chinese characteristics had been formed gradually since then. Some results have provoke the attention of foreign colleagues . The third stage is from the end of 1990s up to now, and it is still in progress. This paper tries to review the major advances in marine biogeochemistry studies in China in the recent four years.
II. ADVANCEMENT IN MARINE BIOGEOCHEMISTRY STUDIES IN CHINA
1. Bio-Genic Elements Biogeochemistry in Estuarine and Coastal Sea
The researches made by Chinese scientists into estuarine nutrients in recent years mainly focused on the large estuaries such as the Pearl River Estuary, the Yangtze River Estuary, the Yellow River Estuary and the Jiulong River Estuary, and they fixed their attention on the nutrients fluxes discharging into the sea, the transport mechanism and the controlling process. Of all estuaries, more attention had been paid to the Pearl River Estuary because of its special geographical position and complexity. Based on the field observations and in situ incubation experiments in summer of 1998 and 1999 along the Pearl River Estuary and adjacent coastal waters of the South Hong Kong, Yin et al. (2000, 2001) indicated that the nutrient limiting factor shifted across the coastal plume from the P limitation in the estuary to the N limitation in the oceanic waters in the Pearl River Estuary. The potential P limitation was observed in the estuary; the P and Si co-limiting occurred at the edge of the coastal plume, and N was the limiting factor in the oceanic side. This kind of limitation characteristics was also found in the Shuangtaizihe River in the Northern China by Zhang J (1999). Zhang et al. (1999, 2000) also reported the nutrients limitation characteristics in the Pearl River Estuary. Furthermore, they found that in eutrophic estuarine and coastal waters, trace elements of Cu2+ and Fe2+ have important impact on the photosynthesis, with Fe2+ being a more important limiting element than Cu2+. Moreover, Liu et al. (2001) estimated the dissolved inorganic nutrients fluxes of the Yangtze River into its estuary. According to the calculation of Duan et al. (2000), about 774.90 × 103, 55.38 × 103 and 144.55 × 103 tons of dissolved inorganic nitrogen (DIN) were discharged into their respective estuaries each year by the Yangtze River, Yellow River and Pearl River in 1980–1989, mainly in the form of nitrate (> 80%). A positive relationship is observed between the annual DIN transport amount of the Yangtze River and the annual application amount of chemical fertilizers in its catchment, and the annual DIN loads of the Yellow River and Pearl River were influenced mainly by runoff and also by application amount of chemical fertilizers.
In recent years, more attention has been paid to the changes of nutrient concentrations and structure under the influence of human activities. This is the prominent characteristics of nutrient research in bay and coastal sea in China. For example, based on the analysis of two observatal reports in the Bohai Sea in 1998-1999 and a 20-year time series data of nutrients and biological parameters, Yu et al. (2001) indicated that both concentration and relative content of nutrients have been changed dramatically in the central Bohai Sea in the recent 20 years. The increase of nitrogen and decrease of phosphate and silicate led to the dramatically increase of the N/P ratio and the decrease of Si/N ratio. The situation of nitrogen limiting in the central Bohai Sea is gradually changing to that of relative lack of phosphate and silicate. And they indicated that the decrease of silicate might be the major factor for the high frequency of red tide in the Bohai Sea in recent years. Shen et al. (2001) also found that nutrient concentrations, nutrient ratios and phytoplankton composition had notably changed in Jiaozhou Bay, Qingdao in the Northern China since the 1960s. The prominent feature is the notable increase of nitrogen and phosphate concentration, and the possibility that nitrogen and/or phosphate as primary production limiting factors in Jiaozhou Bay have been decreased or eliminated and that of silicate limiting has been increased. On the aspect of associating the changes of nutrient concentrations and structure (composition) with ecosystem structure evolution in larger time scale, these researches undoubtedly is a beneficial try.
Chinese scholars started the research into the transportation of nutrients to the ocean via atmosphere and its influence to the marine ecosystem in recent years. Zhang et al. (1999, 2000) monitored the atmospheric wet deposition at three stations in the Yellow Sea, and studied the ion composition, ion balance and the element fluxes of wet deposition (rainwater). The results showed that there are clear seasonal variations for most of the ions, and the concentrations of major ions from urban areas rainwater were apparently higher than that of remote regions. By in situ incubation experiments in the coastal Yellow Sea, Zou et al. (2000) indicated that the atmospheric deposition with high nitrogen and low phosphorus in the Yellow Sea area was the major nutrient resource for phytoplankton in the mixed layer during the water stratification period in summer. Zhang et al. (1999) also indicated that atmospheric wet deposition may well stimulate the phytoplankton photosynthesis in the Pearl River Estuary area, and its impact on the photosynthesis increases from estuary toward the coastal sea.
The study of carbon biogeochemistry on the South China Sea is a very active field in recent years, and one of the most important advances is the finding of influence of East Asia monsoon to the primary production through the analysis of the sediment trap experiments data. Chen et al. (1998,1999)estimated the primary productivity in the South China Sea and its output at the surface layer based on the data of sediment trap experiments, and they found that these two kinds of productivity increased obviously in monsoon time. On the basis of the data of 1993-1995, Wang et al. (2000) indicated that seasonal variations of radiolarian and diatom fluxes in the central South China Sea were o verwhelmingly controlled by the monsoon climate, and they increased during the Northeast (from November to February in next year) and Southwest (from June to September) monsoons and decreased during the periods between the monsoons. The high radiolarian flux corresponds to the high surface primary productivity. The change of circulation driven by the monsoons improves water exchange in the different areas that brings rich nutrients for the surface phytoplankton, thereby enhancing primary productivity and increasing diatom fluxes.
2. Biogeochemistry of Heavy Metals
Zhang et al. (1999,2000) determined the heavy metal concentrations of suspended particulates and sediments from large and middle size in Chinese estuaries to understand trace metal transport in the coastal zone. The results have showed that trace metal concentrations in Chinese rivers are of relatively low compared with those draining industrialized regions in Europe and North America. In these estuaries, the concentration distributions for most particulate heavy metals are of stable distribution pattern in the mixing zone until a salinity of 30. The mean enrichment factor (EFm) increases with higher sewage to the river runoff ratio (S/R) over the drainage basin and EFm for suspended matter is higher than that for bottom sediments. Chen et al. (2000) researched the trace elements in sediments from 12 major rivers in the eastern China, and found that the geographical variations of sediment-bound trace metals can be related to the bedrock types and weathering processes in the corresponding river basins. The rivers in the southern China had notably higher concentrations of trace metals in sediments, and a large proportion of trace metals in these sediments were associated with iron and manganese oxides and organic matter. Relative low concentrations of trace metals were found in river sediments in the northern China, and a significant proportion of the metals were bound to organic matter, carbonates, and the residual fraction. Moreover, Zhang et al. (1999) investigated the distribution of aluminum in four Chinese estuaries such as the Yalujiang River, the Jiaojiang River, etc., and indicated that aluminum is not dominantly coupled to the cycle of nutrients.
Wang Wenxiong and his co-workers carried out the systematic researches into the trace metal-biota interaction in the aquatic environments. They found that metal uptake by aquatic invertebrates (mainly the bivalves) from different exposure pathways is additive and that there is no direct interaction between different routes of exposure, and the increase of metal concentration in phytoplankton cells could decrease the assimilation efficiency (2002, 1999, 2000, 2001). Through researching the influences of sediment geo-chemical factors on metal bio-availability, they found that sediment is a potentially important source for metal uptake in aquatic organism especially the benthic invertebrates (1998, 1999, 2001). Especially, it is worthy of mention that they systematically researched the roles of macronutrient in the metal biological cycling in the marine environments (Lee W.T., 2001). They used different kinds of microplankton and macroalgae as the experiment materials, and found that macronutrients could markedly influence the rate of metal accumulation in the algae. In general, the increase in the ambient nitrate concentration could result in an increase in accumulation, especially the Cd accumulation, and the accumulation of heavy metal was not appreciably affected by the concentration of ammonium. The influences of increased phosphorus and silicate concentration on the Cd, Cr and Zn accumulation in algae were highly species-specific, but the accumulation of Se (IV) in algal cell was always inhibited. Their research demonstrated that nutrient variations in many coastal waters not only change the biological production and ecosystem structure, but also affect the biological transport and fate of heavy metals in eco-system.
3. Isotope Geochemistry
Marine isotope tracer technique is widely applied to the study of water-mass movement, particle dynamics, marine biological production, sediment dynamics etc.
In the recent years, Huang et al. (2001) studied the new method of rapid concentration and determination of radio-nuclide 224Ra in seawater. 224Ra has a short half-life and is suitable for the short-time scale marine process tracer. Chen et al. (1998) investigated the distribution of 224Ra in the Jiulong estuarine and indicated that 224Ra is non-conservative in this area. They estimated the seaward current speed in the Jiulong estuarine based on the dissolved 224Ra data. Moreover, they calculated the vertical eddy diffusion coefficient and its spatial distribution of 224Ra in Xiamen Bay(1999). Furthermore, the isotope tracer technique was used to evaluate the flux of particulate organic carbon and new productivity, and distinguish matter source. Cai et al. (2000) reported the primary productivity measured by the 14C method at 10 stations in the Nansha area of the south China Sea and indicated that it was a typical oligotrophic area. The quantitative relationship between the primary productivity and vertical stability of water column was indicated for the first time in China. Cai et al. (2000) used 228Ra, 228Th and 234Th to estimate new productivity and output flux of POC in the South China Sea, and calculated the upward flux of nitrate into the euphotic zone by the coupled 228Ra-nitrate approach and further converted it into corresponding new production based on the Redfield ratio. Lee (2000) studied the sources of nutrients by using the stable isotopes of carbon and nitrogen, and indicated that the nutrients in deep bay in the eastern Pearl River Estuary were mainly from the input of anthropogenic particular organic matter and benthic algae. Wu et al. (2001) researched the carbon isotope geochemistry in the Yalujiang Estuary, and indicated that the POC in the Yalujiang Estuary is predominantly of terrestrial origin rather than a result of in situ plankton, and the turbidity maximum plays an important role in the POC cycle in the Yalujiang Estuary.
Significant progress has been achieved on the study of particulate materials scavenging and output process based on the 234Th/238U disequilibria in water. Chen et al. (1998) and Cai et al. (2001, 2002) investigated the 234Th and 238U in the South China Sea and Xiamen Bay. The results showed that there were different 234Th/238U disequilibria degree and vertical profiles in deep sea and coastal shallow sea. The total concentration 234Th showed evident deficit relative to total concentration of 238U in the euphotic zone in deep sea area, and they got secular equilibrium in water under euphotic zone, meanwhile, the main form is dissolved 234Th. The dissolved, particulate and total 234Th were insufficient in comparison with the equilibrium value of 238U in the whole water column in coastal shallow sea area, and the deficiency degree was higher than that in deep-sea area.
4. Biogeochemistry of Organic Pollutants
In recent years, with the increasing attention given to environmental problems, Chinese scholars have paid more attention to environmental contamination, especially the organic pollutants such as PAHs, PCBs, DDTs and HCHs. The studies are focused on the concentration, distribution and source analysis of organic pollutants in sediment in bay, estuary and coastal sea. As for the study area, almost all work was done in the southern China.
The distribution, concentration and source of the organic pollutants in water, sediment, sediment pore water and SPM were studied in the Xiamen sea area, Jiulong River Estuary and Minjiang River Estuary (Yuan 2001, Hong 2000, Zhou 2000, Wang 1999), Pearl River Estuary, Daya Bay and its adjacent sea area (Yuan 2001; Hong 2000, 1999; Mai 2002, 2001; Fu 2001; Kang 2000, 2001; Zhou 2001), Yangtze River Estuary tide flat (Liu et al., 2000, 2001), South China Sea by Yang (2000), tideland of the Bohai Sea and Yellow Sea by Ma et al. (2001), and seven river and estuary systems in the northern China by Wu et al. (1999). The results showed that organic pollution levels in the above study areas in China were relatively low compared with the world's other river/estuary systems. It is probably the results of the decrease of pollution in recent years as well as the degradation of pollutants over a period of time.
The heterocyclic sulfur polynuclear aromatic compounds have received increasing attention in recent years because of their carcinogenic and mutagenic properties combined with their nearly ubiquitous distribution in the depositional environments. Yang et al. (2000, 1998) took the lead in researching this kind of compound in marine sediment in China. They investigated the distribution and concentration of dibenzothiophene in sediments in the South China Sea, and indicated that the clay and organic carbon contents are two key factors controlling the dibenzothiophene levels in sediment. Furthermore, according to the vertical variations of organic pollutants in sedimentary cores dated by the high precision radioactive isotope 210Pb, Chen et al. (1999) reconstructed the organic pollution history by the molecular (element) stratigraphical records. Kang et al. (2000) did the similar work in the Macao Estuary, Pearl River Delta. These works provided cases of reconstructing the coastal sea pollution history and evaluating the variation of environmental load by using the molecular (element) stratigraphical record methods in China.
5. Organic Geochemistry
Organic composition in sediment is regarded as the major research objective of marine organic geochemistry, and the studies are focused on frequent biomarkers of n-alkanes, isopreniod, fatty acid, steranes, terpanes and so on. Studies of these biomarkers provide useful information for analysing the matter input, the sedimentary environment, the sedimentary maturity and the early diagenetic evolution process(Wu et al. ,1999). In recent years, Xu, Mao, Guo, Wu and Duan et al.(1999,2001,2000) investigated the concentration, distribution and sources of organic matter in the Xiamen-Jinmen area, the Yangtze River and Yellow River estuaries, the mud areas in the East China Sea shelf and sediments of the South China Sea, respectively. Kang et al. (2000) researched the concentrations and different distribution patterns of n-alkanes in sediment core from the Macao Estuary, Pearl River, and they further discussed the sources of organic pollutants based on the factor analysis of data and reconstructed the sedimentary history of n-alkanes dated by the radioactive isotope 210Pb.
Sterol (4α, 23, 24-trimethyl-5α-cholest-22-en-3β-ol) is commonly regarded as a relatively good indicator for dinoflagellate. However, whether it can exactly indicate the distributions and variations of dinoflagellate remains controvertible. Peng et al. (1998) determined the concentrations of this sterol in SPM and analyzed its indication to dinophyceae in the Taiwan Strait, and the results showed that the quantitatively indicating function of this compound should be made clear.
Chen et al. (2000) analyzed the amino acids and carbohydrates in settling planktonic shells collected by the time series sediment trap in the South China Sea, and found that planktonic shells could preserve more intact and fresh matrix than that of total particulate matter. It showed that settling planktonic shells might act as very important carriers for the vertical transportation of organic carbon.
6. Biogeochemistry of Greenhouse Gases
Researching the transfer and fate of CO2 in the ocean, i.e. the oceans' capacity to take up and transfer atmospheric CO2 and the mechanism of CO2 cycle in ocean, has become one of the important content of marine science in the world. Han et al. (1998) researched the air-sea exchange of CO2 in the South China Sea, and indicated that the South China Sea is a source in the global CO2 exchange at the air-sea interface, but if the carbon carried by rainwater into the South China Sea was regarded as one part of air-sea exchange, then the net direction of carbon exchange would be from atmosphere to the sea. Hu et al. (2001) conducted a multi-disciplinary study of the key process controlling the oceanic flux in East China Sea ocean fluxes. Based on the calculation of partial pressure data of CO2 in field in four quarters, they drew a conclusion that the East China Sea absorbed 4.3 million tons carbon each year from atmosphere and was the weak sink of atmospheric CO2 (it is a sink in spring and summer and a source in fall and winter). It provides a new proof for the discussion of the worldwide burning issue “whether the continental shelf sea is the whither of missing term” in the global carbon circulation.
Atmospheric CO2 is transferred into seas through the air-sea interface, and transformed to carbonic compounds through the processes of oceanic circulation, marine biological and chemical processes, then goes into deep sea from upper layer. This vertical transport of carbon is the process of “bio-pump”. In model research, Xing Jin et al. (2000, 2001) respectively established a 3D global oceanic carbon circulation model with bio-pump to simulate marine biogeochemistry of carbon, and proved that marine biological process plays an important role in the uptake of atmospheric CO2 by ocean through the comparison experiments with and without bio-pump.
CH4 and N2O are also the greenhouse gases and have far larger index of the greenhouse effect than that of CO2. DMS has the negative greenhouse effect, and its major functions in atmospheric chemistry and global biogeochemistry are decreasing the climate warming effect. These three gases are studied frequently in recent years. Ye et al. (2000) studied the spatial seasonal and variations of CH4 emissions from mangrove wetlands along estuary and coastal sea in the Hainan Island and Xiamen. Lu et al. (2000) researched the CH4 fluxes from sediments of mangrove communities in the Hainan Island, and the results showed that there were two different seasonal patterns of CH4 flux from soils because of different vegetation types or soil properties. DMS in seawater is produced through marine biodegradation. Yang, Jiao and Fang et al. (2000,1999,1998) studied the determination method, distribution, transformation and sources. They determined the concentration and distribution of DMS in the East China Sea, the South China Sea and the Qingdao coastal sea areas, and indicated that the seasonal variability of the DMS concentration in the high latitude sea area is higher than that in the tropic area. They found that the DMS concentrations are associated with such environmental factors as seawater temperature, dissolved O2 and nutrient concentrations. DMS is highly correlated to chlorophyll a. However, some further researches have shown that the phytoplankton species is the major factor responsible for the markedly higher DMS concentration rather than the expected phytoplankton biomass. In addition, Lin et al.(2001), Hu et al.(1998) and Li et al. (1999)experimentally studied the production of DMS and DMSP of marine phytoplankton (Alexandrium tamarense, Chaetoceros sp., Amphidinium hoefleri and so on).Acknowledgement: The effort of Mr. ZOU Weiming in proofreading of this English text is appreciated.
REFERENCESCai, P. H., Huang, Y. P., Chen, M., et al. (2001), Export of particulate organic carbon estimated from Th-234-U-238 disequilibria and its temporal variation in the South China Sea, Chinese Science Bulletin, 46(20): 1722-1726.Cai, P. H., Huang, Y, P,, Chen, M., et al.(2002), New production based on Ra-228-derived nutrient budgets and thorium-estimated POC export at the intercalibration station in the South China Sea , Deep-Sea Research I, 49(1): 53-66.Cai, P. H., Huang, Y. P., Shen, G. Y., et al. (2000), The relationship between primary productivity and vertical stability of water column in the South China Sea, Acta Oceanologica Sinica, 22(5):137-140 (in Chinese).Chen, J. F., Chen, R. H., Wiesner, M, G., et al.(2000), Amino acids, amino sugars and carbohydrates in settling planktonic tests and their implications for the South China Sea, Oceanologia et Limnologia Sinica, 31(6):596-603 (in Chinese).Chen, J. F., Ye, X. R., Zhou, H. Y., et al. (1999), Preliminary study on the marine organic pollution history in Chanjiang Estuary –Hangzhou Bay BHC and DDT stratigraphical records, China Environmental Science, 19(3): 206-210 (in Chinese).Chen, J. F., Zheng, L. F., Wiesner, M. G., et al. (1998), Estimation of primary production and export production in the South China Sea based on sediment trap experiments, Chinese Science Bulletin, 43:583-586.Chen, J. F., Zheng, L. F., Wiesner, M. G., et al. (1998), Estimation of primary production and export production in the surface layer of the South China Sea based on sediment trap experiments, Chinese Science Bulletin, 43(6): 639-642(in Chinese).Chen, J. S., Wang, F. Y., Li, X. D., et al. (2000), Geographical variations of trace elements in sediments of the major rivers in eastern China, Environmental Geology, 39:1334-1340.Chen, M. and Huang, Y. P. (1998), Fate of particle-reactive pollutants in the Xiamen Bay, Acta Oceanologica Sinica, 17(4): 503-508.Chen, X. B., Xie, Y. Z., et al. (1998), Profiles of 224Ra in the Xiamen Bay waters and its application, Acta Oceanologica Sinica, 20(6): 50-57 (in Chinese).Chen, X. B., Xie, Y. Z., H uang, Y. P., et al. (1999), Distribution of 224Ra in the Jiulong Estuarine waters and its application, Acta Oceanologica Sinica, 21(4): 54-61 (in Chinese).Chong, K. and Wang, W. X. (2000), Assimilation of Cd, Cr, and Zn by the green mussel Perna viridis and the clam Ruditapes philippinarum, Environmental Toxicology and Chemistry, 19(6): 1660-1667.Duan, S. W., Zhang, S. and Huang, H. Y. (2000), Transport of dissolved inorganic nitrogen from the major rivers to estuaries in China, Nutrient Cycling in Agroecosystems, 57(1): 13-22.Duan, Y. (2000), Organic geochemistry of recent marine sediments from the Nansha Sea, China, Organic Geochemistry, 31:159-167 (in Chinese).Fan, W. H. and Wang, W. X. (2001), Sediment geochemical control on Cd, Cr, and Zn assimilation by the clam Ruditapes philippinarum , Environmental Toxicology and Chemistry, 20: 2309-2317.Fang, C., Hu, M., Zeng, L. M., et al. (1998), Determination of dimethyl sulfide in sea water, Acta Scientiarum Naturalium Universitatis Pekinensis, 34(4): 461-466 (in Chinese).Fu, J., Wang, Z., Mai, B., et al. (2001), Field monitoring of toxic organic pollution in the sediments of Pearl River estuary and its tributaries, Water Science & Technology, 43:83-89.Guo, Z. G., Yang, Z. S., Chen, Z. L., et al. (2001), Source of organic matter in the mud areas of the East China Sea Shelf, Geochimica, 30(5): 416-424 (in Chinese).Han, W. Y. (1998), Marine chemistry in the South China Sea, Science Press, Beijing, (in Chinese).Hong, H. S., Chen, W. Q., Xu, L., et al. (1999), Distribution and fate of organochlorine pollutants in the Pearl River estuary, Marine Pollution Bulletin, 39:376-382.Hong, H. S., Wang, X. H., Xu, L., et al. (2000), Trace organic pollutants in the southeast estuarine environments of China, Journal of Environmental Science and Health Part A-Toxic/Hazardous Substances& Environmental Engineering, 35:1833-1847.Hu, D. X. and Yang, Z. S. (2001), Key process of ocean fluxes in the East China Sea, Ocean Press, Beijing, (in Chinese).Hu, M., Ren C. J., Jiang, L., et al. (1998), A study on DMS producing by marine algae, Amphidinium hoefleri and Chaetoceros gracilis , Environmental science, 19(6):6-9 (in Chinese).Huang, Y. P., Chen, X. B., et al. (2001), A new method for rapid concentration and determination of 224Ra in seawater, Journal of Xiamen University (natural science), 40:60-66 (in Chinese).Jiao, N. Z., Liu, C. Z.and Chen, N. H. (1999), Distribution of dimethylsulphonio propionate and it controlling mechanism in the East China Sea, Oceanologia et Limnologia Sinica, 30(5):525-531 (in Chinese).Jin, X. and Shi, G. Y. (2000), A simulation of CO2 uptake in a three-dimensional world ocean carbon cycle model, Acta Meteorologica Sinica, 58(1):40-48 (in Chinese).Jin, X. and Shi, G. Y. (2001), The role of biological pump in ocean carbon cycle, Chinese Journal of Atmospheric Sciences, 25(5): 683-688 (in Chinese).Kang, Y. H., Mai, B. X. (2000), Distribution characteristics of organochlorinated pesticides in sediment from Pearl River Delta Estuary and its adjacent sea areas , China Environmental Science, 20(3):245-249 (in Chinese).Kang, Y. H., Sheng, G. Y., Fu, J. M., et al. (2001), Vertical distribution characteristics of organochlorinated pesticides in sediment core from Macao Estuary, Pearl River Delta, Environmental Science, 22(1): 81-85 (in Chinese).Kang, Y. H., Sheng, G. Y., Fu, J. M., et al. (2000), The study of n-alkanes in a sedimentary core from Macao Estuary, Pearl River, Geochimica, 29(3): 302-310 (in Chinese).Kang, Y. H., Sheng, G.Y. and Fu, J. M. (2000), Polychlorinated biphenyls in surface sediments from the Pearl River delta and Macau, Marine Pollution Bulletin, 40:794-797.Lee, S. Y. (2000), Carbon dynamics of Deep Bay, eastern Pearl River estuary, China. II: Trophic relationship based on carbon- and nitrogen-stable isotopes, Marine Ecology Progress Series, 205:1-10.Lee, W. Y. and Wang, W. X. (2001), Metal accumulation in the green macroalga Ulva fasciata: effects of nitrate, ammonium and phosphate, Science of the Total Environment, 278(1-3): 11-22.Li, W. and Jiao, N. Z. (1999) experimental studies on environmental factors regulating intracellular dimethylsulphoniopropionate of three unicellular algae species, Oceanologia et Limnologia Sinica, 30(6): 635-639 (in Chinese).Lin, Y. M., Li, H. Y., Wang, D. Z., et al. (2001), Study on DMS and DMSP producing by Alexandrium tamarense, Journal of Oceanography in Taiwan Strait, 20(3): 335-339 (in Chinese).Liu, M., Baugh, P. J. and Hutchinson, S. M. (2000), Historical record and sources of polycyclic aromatic hydrocarbons in core sediments from the Yangtze Estuary, China, Environmental Pollution, 110:357-365.Liu, M., Hou, L. J., Yang, Y., et al. (2001), Distribution and sources of polycyclic aromatic hydrocarbons in intertidal flat surface sediments from the Yangtze estuary, China, Environmental Geology, 41: 90-95.Liu, X. C. and Shen, H. T. (2001), Estimation of dissolved inorganic nutrients fluxes from the Changjiang River into estuary, Science in China series B, 44 (suppl.): 135-141.Lu, C. Y., Ye, Y., Huang, Y. S., et al. (2000), Methane fluxes from mangrove communities at Dongzhai Harbour, Hainan, Acta Phytoecologica Sinica, 24(1): 87-90 (in Chinese).Ma, M. H., Feng, Z, Q., Guan, C. J., et al. (2001), DDT, PAH and PCB in sediments from the intertidal zone of the Bohai Sea and the Yellow Sea , Marine Pollution Bulletin, 42:132-136.Mai, B. X., Fu, J. M., Sheng, G. Y., et al. (2002), Chlorinated and polycyclic aromatic hydrocarbons in riverine and estuarine sediments from Pearl River Delta, China, Environmental Pollution,117: 457-474.Mai, B. X., Fu, J. M., Zhang, G., et al. (2001), Polycyclic aromatic hydrocarbons in sediments from the Pearl river and estuary, China: spatial and temporal distribution and sources, Applied Geochemistry, 16:1429–1445.Mao, D., Fan, D. J., Guo, Z. G., et al. (2001), Preliminary study on biomarker in surface sediments from mouths of the Changjiang River and the Huanghe River, Journal of Ocean University of Qingdao, 31(5):747-754 (in Chinese)。Peng, X. Y., Xu, L., Zhang, Z. L., et al.(1998)), 4α, 23, 24-trimethyl-5α-cholest-22-en-3β-ol, -a dinoflagellate indicator, in suspended particles in Taiwan Strait , Journal of Xiamen University (natural science), 37(4):563-568 (in Chinese).Shen, Z. L. (2001), Historical changes in nutrient structure and its influences on phytoplantkon composition in Jiaozhou Bay , Estuarine Coastal and Shelf Science, 52(2): 211-224.Wang, R. J., Lin, J., Zheng, L. F., et al. (2000), Siliceous microplankton fluxes and seasonal variations in the central South China Sea during 1993-1995: monsoon climate and El Nino responses, Chinese Science Bulletin, 45(23): 2168-2172.Wang, W. X. and Dei, R. C. H. (2001), Influences of phosphate and silicate on Cr (VI) and Se (IV) accumulation in marine phytoplankton , Aquatic Toxicology, 52: 39-47.Wang, W. X., Dei, R.C.H. and Xu Y. (2001), Cadmium uptake and trophic transfer in coastal plankton under contrasting nitrogen regimes, Marine Ecology Progress Series, 211: 293-298.Wang, W. X., Dei, R. C. H. and Xu, Y. (2001), The responses of Zn assimilation by coastal plankton to macronutrients, Limnology&Oceanography, 46: 1524-1534.Wang, W. X., Dei, R. C. H. (2001), Biological uptake and assimilation of iron by marine plankton: influences of macronutrients, Marine Chemistry, 74: 213-226.Wang, W. X., Dei, R. C. H. (2001), Effects of major nutrient additions on metal uptake in phytoplankton, Environmental Pollution, 111: 233-240.Wang, W. X. and Dei, R. C. H. (1999), Factors affecting trace element uptake in the black mussel Septifer virgatus, Marine Ecology Progress Series, 186: 161-172.Wang, W.X., Dei, R. C. H. (2001), Metal uptake in a coastal diatom influenced by major nutrients (N, P, Si), Water Research, 35: 315-321.Wang, W. X., Stupakoff, I., Fisher, N. S. (1999),Bioavailability of dissolved and sediment-bound metals to a marine deposit-feeding polychaete , Marine Ecology Progress Series, 178: 281-293.Wang, W. X., Stupakoff, I., Gagnon, C., et al. (1998), Bioavailability of inorganic and methylmercury to a marine deposit-feeding polychaete , Environmental Science and Technology, 32(17): 2564-2571.Wang, W. X. (2002), Cd and Se aqueous uptake and exposure of green mussels Perna viridis: influences of seston quantity, Marine Ecology Progress Series, 226:211-221.Wang, W. X. (2001), Comparison of metal uptake rate and absorption efficiency in marine bivalves, Environmental Toxicology and Chemistry, 20(6): 1367-1373.Wang, X. H., Xu, L., Chen, W. Q., et al. (1999), The vertical distributions and sources of PAHs in sediment of Xiamen Bay, Chinese Journal of Oceanology&Limnology, 17:247-251.Wu, Y., Zhang, J. and Tang. Y. Q. Advance in marine organic geochemical studies of China, Advance in Earth Sciences, 1999, 14(3): 256-261 (in Chinese).Wu , Y., Zhang, J. and Zhou, Q. (1999),Persistent organochlorine residues in sediments from Chinese river/estuary systems , Environmental Pollution, 105:143-150.Wu, Y. and Zhang. J. (2001), Carbon isotope geochemistry in the Yalujiang estuary. Science in China Series B, 44(suppl.): 173-177.Xing, R. N. (2000), A three-dimensional world ocean carbon cycle model with ocean biota pump, Chinese Journal of Atmospheric Sciences, 24(3): 333-340 (in Chinese).Xu, L., Zhang, L. P., Wang, X. H, et al. (1999), Sources and distribution features of hydrocarbons in Xamen-Jinmen area, Journal of Xiamen University (natural science), 38(5): 738-744 (in Chinese).Xu, Y., Wang, W. X. and Hsieh, D. P. H. (2001), Influences of metal concentration in phytoplankton and seawater on metal assimilation and elimination in marine copepods, Environmental Toxicology and Chemistry, 20(5): 1067-1077.Yang, G. P., Liu, X. L. and Zhang, J. W. (1998), Distribution of dibenzothiophene in the sediments of the South China Sea, Environmental Pollution, 101:405-414.Yang, G. P., Liu, X. T.and Zhang, Z. B. (1999), Biogeochemistry of dimethylsulfide in the South China Sea, Journal of Marine Research, 57:189-211.Yang, G. P., Zhang, J. W., Li, L. et al. (2000), Dimethylsulfide in the surface water of the East China Sea, Continental Shelf Research, 20:69-82.Yang, G. P. (2000), Polycyclic aromatic hydrocarbons in the sediments of the South China Sea, Environmental Pollution, 108:163-171.Yang, G. P. (2000), Spatial distributions of dimethylsulfide in the South China Sea, Deep Sea Research I, 47:177-192.Ye, Y., Lu, C. Y. and Lin, P. Seasonal and spatial changes of methane emissions from mangrove wetlands in Hainan Island and Xiamen, Chinese Journal of Atmospheric Sciences, 2000. 24(2): 152-156 (in Chinese)Yin, K. D., Qian, P. Y., Chen, J. C., et al. (2000), Dynamics of nutrients and phytoplankton biomass in the Pearl River estuary and adjacent waters of Hong Kong during summer: preliminary evidence for phosphorus and silicon limitation, Marine Ecology Progress Series, 194:295-305.Yin, K. D., Qian, P. Y., Madeline, C. S., et al. (2000), Shift from P to N limitation of phytoplankton growth across the Pearl River estuarine plume during summer, Marine Ecology Progress Series, 221:17-28.Yu, Z. G., Mi, T. Z., Yao, Q. Z., et al. (2001), The nutrients concentration and the changes in decade-scale in the central Bohai Sea , Acta Oceanologica Sinica, 20(1): 65-75.Yuan, D. X., Yang, D. N., Wade, T. L., et al. (2001), Status of persistent organic pollutants in the sediment from several estuaries in China, Environmental Pollution, 114:101-111.Zhang, J. L., Yu, Z. G. and Zhang, J. (2000), Wet deposition (precipitation) of major elements at two sites of Northwestern Yellow Sea, Environmental Chemistry, 19(4): 352-356 (in Chinese).Zhang, J., Chen, S. Z., Yu, Z. G., et al. (1999), Factors influencing changes in rainwater composition from urban versus remote regions of the Yellow Sea, Journal of Geophysical Research -Atmospheres, 104(1): 1631-1644.Zhang, J. and Liu, C. L. Riverine Composition and Estuarine Geochemistry of Particulate Metals in China-Weathering Features, Anthropogenic Impact and Chemical Fluxes, Estuarine, Coastal and Shelf Science, 2002, 54(6): 1051-1070.Zhang, J., Xu H., Yu, Z, G., et al. (1999), Dissolved aluminum in four Chinese estuaries: evidence of biogeochemical uncoupling of Al with nutrients, Journal of Asian Earth Sciences, 17 (3): 333-343.Zhang, J., Xu, J., Liu, S. M., et al. (1999), Nutrient Element Distributions in the Mesotidal Shuangtaizihe Estuary from North China, Journal of Coastal Research, 15(2): 526–536.Zhang, J., Yu, Z. G., Wang, J. T., et al. (1999), The subtropical Zhujiang (Pearl River) Estuary: Nutrient, trace species and their relationship to photosynthesis, Estuarine, Coastal and Shelf Science, 49(3): 385-400.Zhang, J. (2000), Evidence of trace metal limited photosynthesis in eutrophic estuarine and coastal waters, Limnology&Oceanography, 45(8): 1871–1878.Zhang, J. (1999), Heavy metal compositions of suspended sediments in the Changjiang (Yangtze River) estuary: significance of riverine transport to the ocean, Continental Shelf Research, , 19: 1521-1543.Zhou, J. L., Hong, H., Zhang, Z. (2000), Multi-phase distribution of organic micropollutants in Xiamen Harbour, China, Water Research, 34:2132-2150.Zhou, J. L., Maskaoui, K., Qiu, Y. W. (2001), Polychlorinated biphenyl congeners and organochlorine insecticides in the water column and sediments of Daya Bay, China, Environmental Pollution, 113:373-384.