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Jianlin Zhang

Bio: Jianlin Zhang is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Phytoplankton & Upwelling. The author has an hindex of 10, co-authored 13 publications receiving 524 citations.

Papers
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Journal ArticleDOI
15 Feb 2010
TL;DR: The dynamics of size-fractionated phytoplankton along the salinity gradient in the Pearl River Estuary and the adjacent near-shore oceanic water was investigated using microscopic, flow cytometric, and chlorophyll analyses in the early spring (March) and early autumn (September) of 2005 as mentioned in this paper.
Abstract: The dynamics of size-fractionated phytoplankton along the salinity gradient in the Pearl River Estuary and the adjacent near-shore oceanic water was investigated using microscopic, flow cytometric, and chlorophyll analyses in the early spring (March) and early autumn (September) of 2005. In the inner part of the estuary where salinity was less than 30, the phytoplankton community was dominated by micro- and nano-sized (3-200 mu m) cells, particularly the diatom Skeletonema costatum, both in early spring and early autumn. In areas where salinity > 30, including the mixing zone and nearshore oceanic water, micro- and nano-sized cell populations dominated the phytoplankton assemblage during early spring when influence of river discharge was minimal, whereas pico-sized ( 30) areas as a result of short residence time, exerting a strong influence on phytoplankton abundance, especially picophytoplankton in the nearshore, otherwise oligotrophic, water. Influenced by high abundance of DIN and limitation in phosphorus, picophytoplankton in the adjacent nearshore oceanic water rose to prominence seasonally. Our results indicate that eutrophication in the Pearl River Estuary not only stimulates the growth of S. costatum in the nutrient-rich areas of the estuary but also appears to promote the growth of Synechococcus and pico-eukaryotes in the adjacent usually oligotrophic oceanic water at least during our autumn cruise. (C) 2009 Elsevier Ltd. All rights reserved.

113 citations

Journal ArticleDOI
01 Oct 2004
TL;DR: In this article, the authors investigated the spatial distribution of primary productivity, and two size fractionations (5 pm) of chlorophyll in the Pearl River estuary and across the coastal plume south of Hong Kong during the season of high river discharge (July, 1999 and 2000).
Abstract: The Pearl River estuary fuels phytoplankton productivity in the estuarine coastal waters in the oligotrophic South China Sea. Cruises were conducted to investigate the spatial distribution of primary productivity, and two size fractionations ( 5 pm) of chlorophyll in the Pearl River estuary and across the coastal plume south of Hong Kong during the season of high river discharge (July, 1999 and 2000). During 18-19 July 1999, phytoplankton biomass and productivity were low in the freshwater dominated estuary ( 5 mum size fractionation (> 50%). The Pearl River estuary displayed a typical spatial variability of phytoplankton biomass: low biomass and productivity due to rapid dilution and light limitation in turbid estuarine waters, a regional maximum of biomass and productivity at intermediate salinities in the coastal plume and low biomass due to nutrient limitation in oceanic waters. In summer when south-southwest monsoonal winds blow, part of the coastal plume moves eastwards. A regional maximum of phytoplankton usually develops in the coastal plume south of Hong Kong. However, a change in wind direction to the east or northeast can cause the following effects: pushing the coastal plume westward to the estuary, holding (retaining) the estuarine plume in the estuary (due to the Coriolis effect) and at the same time, mixing the water column vertically. Such a strong east or northeast wind event was observed during July 22-26 1999 and caused an increase in salinity at the surface in the estuary compared to before the wind event. This wind event increased the residence time of the estuarine plume inside the estuary, and as a result, a phytoplankton bloom (52-151 mg chl am(-2)) developed during July 25-26 inside the estuary. This similar easterly wind effect was observed during July 2000. After a strong easterly wind event (speed 10 ms(-1)) on July 11, the coastal plume was absent in waters south of Hong Kong on July 13, but it returned on July 19 after winds blew from the south and southwest direction. The results suggest that wind events not only changed the spatial movement of the coastal plume, but also the spatial distribution of phytoplankton biomass and productivity in the Pearl River estuary and adjacent coastal waters. (C) 2004 Elsevier Ltd. All rights reserved.

109 citations

Journal ArticleDOI
TL;DR: Environmental factors, phytoplankton biomass (Chl a) and primary production of two water areas in Daya Bay were investigated during the transition period from spring to summer, including high values of DO, nitrate and silicate.

97 citations

Journal ArticleDOI
TL;DR: The HAB had complicated relationships with hydrological and meteorological factors in Daya Bay, however, the water around the cage-culture area always showed statistically greater phytoplankton biomass and nutrient loadings than in adjacent waters, suggesting that this was the "trigger area" of the bloom.

76 citations

Journal ArticleDOI
TL;DR: Based on the high-resolution in situ and remote sensing data, this paper examined in details the spatial patterns of phytoplankton biomass and primary production in the coast of NWSCS in summer and discussed the underline physical processes involved.

51 citations


Cited by
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Journal ArticleDOI
TL;DR: The Zhu-jiang (Pearl River) estuary and its adjacent continental shelf in the Northern South China Sea (SCS) is unique in that its drainage basin is located entirely in a subtropical zone with heavy population development, and therefore represents an important regime for biogeochemical studies on how large rivers influence continental shelves.

309 citations

Journal ArticleDOI
Jianfang Hu1, Ping'an Peng1, Guodong Jia1, Bi-Xian Mai1, Gan Zhang1 
TL;DR: The isotopic composition (d 13 C and d 15 N) and organic carbon (OC) and total nitrogen (TN, organic plus inorganic) content of 37 carbonate-free surficial sediments of the subtropical Pearl River estuary and the adjacent shelf of South China Sea (SCS) was determined in this paper.

244 citations

Journal ArticleDOI
15 Jul 2008
TL;DR: The Pearl River Estuary is a subtropical estuary and the second largest in China based on discharge volume from the Pearl River as mentioned in this paper, which shows a remarkable capacity to cope with excessive nutrients.
Abstract: The Pearl River Estuary is a subtropical estuary and the second largest in China based on discharge volume from the Pearl River. Processes in the estuary vary spatially and temporally (wet vs dry season). In the dry season at the head of the estuary, hypoxic and nearly anoxic conditions occur and NH4 reaches > 600 mu M, NO3 is similar to 300 mu M and nitrite is similar to 60 mu M indicating that nitrification and denitrification may be important dry season processes in the region extending 40 km upstream of the Humen outlet. There are very few biological studies conducted in this upper section of the estuary in either the dry or wet seasons and hence there is a need for further research in this region of the river. In the wet season, the salinity wedge extends to the Hongqimen outlet and oxygen is low (35-80% saturation). Nitrate is similar to 100 mu M, silicate similar to 140 mu M: and phosphate is relatively low at similar to 0.5 mu M, yielding an N:P ratio up to similar to 200:1 in summer. Nutrients decrease in the lower estuary and primary productivity may become potentially P-limited. Eutrophication is not as severe as one would expect from the nutrient inputs from the Pearl River and from Hong Kong's sewage discharge. This estuary shows a remarkable capacity to cope with excessive nutrients. Physical processes such as river discharge, tidal flushing, turbulent dispersion, wind-induced mixing, and estuarine circulation play an important role in controlling the production and accumulation of algal blooms and the potential occurrence of hypoxia. Superimposed on the physical processes of the estuary are the chemical and biological processes involved in the production of the bloom. For example, the 100N:1P ratio indicates that P potentially limits the amount of algal biomass (and potential biological oxygen demand) in summer. While extended periods of hypoxia are rare in Hong Kong waters, episodic events have been reported to occur during late summer due to factors such as low wind, high rainfall and river discharge which result in strong density stratification that significantly dampens vertical mixing processes. Nutrient loads are likely to change over the next several decades and monitoring programs are essential to detect the response of the ecosystem due to the future changes in nutrient loading and the ratio of nutrients. (c) 2008 Elsevier Ltd. All rights reserved.

240 citations

Journal ArticleDOI
TL;DR: In this article, the authors present the applicability of δ 13 C and C/N as indicators for sources of organic matter in deltaic and estuarine sediments.
Abstract: Preservation of organic matter in estuarine and coastal areas is an important process in the global carbon cycle. This paper presents bulk δ 13 C and C/N of organic matter from source to sink in the Pearl River catchment, delta and estuary, and discusses the applicability of δ 13 C and C/N as indicators for sources of organic matter in deltaic and estuarine sediments. In addition to the 91 surface sediment samples, other materials collected in this study cover the main sources of organic material to estuarine sediment. These are: terrestrial organic matter (TOM), including plants and soil samples from the catchment; estuarine and marine suspended particulate organic carbon (POC) from both summer and winter. Results show that the average δ 13 C of estuarine surface sediment increases from −25.0 ± 1.3‰ in the freshwater environment to −21.0 ± 0.2‰ in the marine environment, with C/N decreasing from 15.2 ± 3.3 to 6.8 ± 0.2. In the source areas, C 3 plants have lower δ 13 C than C 4 plants (−29.0 ± 1.8‰ and −13.1 ± 0.5‰ respectively). δ 13 C increases from −28.3 ± 0.8‰ in the forest soil to around −24.1‰ in both riverbank soil and mangrove soil due to increasing proportion of C 4 grasses. The δ 13 C POC increases from −27.6 ± 0.8‰ in the freshwater areas to −22.4 ± 0.5‰ in the marine-brackish-water areas in winter, and ranges between −24.0‰ in freshwater areas and −25.4‰ in brackish-water areas in summer. Comparison of the δ 13 C and C/N between the sources and sink indicates a weakening TOM and freshwater POC input in the surface sedimentary organic matter seawards, and a strengthening contribution from the marine organic matter. Thus we suggest that bulk organic δ 13 C and C/N analysis can be used to indicate sources of sedimentary organic matter in estuarine environments. Organic carbon in surface sediments derived from anthropogenic sources such as human waste and organic pollutants from industrial and agricultural activities accounts for less than 10% of the total organic carbon (TOC). Although results also indicate elevated δ 13 C of sedimentary organic matter due to some agricultural products such as sugarcane, C 3 plants are still the dominant vegetation type in this area, and the bulk organic δ 13 C and C/N is still an effective indicator for sources of organic matter in estuarine sediments.

234 citations

Journal ArticleDOI
15 Jul 2008
TL;DR: In this article, the authors examined the occurrence of seasonal hypoxia (O 2 < 2 mg l(-1)) in the bottom waters of four river-dominated ocean margins (off the Changjiang, Mississippi, Pearl and Rhone Rivers) and compared the processes leading to the depletion of oxygen.
Abstract: We examined the occurrence of seasonal hypoxia (O-2 < 2 mg l(-1)) in the bottom waters of four river-dominated ocean margins (off the Changjiang, Mississippi, Pearl and Rhone Rivers) and compared the processes leading to the depletion of oxygen. Consumption of oxygen in bottom waters is linked to biological oxygen demand fueled by organic matter from primary production in the nutrient-rich river plume and perhaps terrigenous inputs. Hypoxia occurs when this consumption exceeds replenishment by diffusion, turbulent mixing or lateral advection of oxygenated water. The margins off the Mississippi and Changjiang are affected the most by summer hypoxia, while the margins off the Rhone and the Pearl rivers systems are less affected, although nutrient concentrations in the river water are very similar in the four systems. Spring and summer primary production is high overall for the shelves adjacent to the Mississippi, Changjiang and Pearl (1-10g C m(-2) d(-1)), and lower off the Rhone River (< 1 g C m(-2) d(-1)), which could be one of the reasons of the absence of hypoxia on the Rhone shelf The residence time of the bottom water is also related to the occurrence of hypoxia, with the Mississippi margin showing a long residence time and frequent occurrences of hypoxia during summer over very large spatial scales, whereas the East China Sea (ECS)/Changjiang displays hypoxia less regularly due to a shorter residence time of the bottom water. Physical stratification plays an important role with both the Changjiang and Mississippi shelf showing strong thermohaline stratification during summer over extended periods of time, whereas summer stratification is less prominent for the Pearl and Rhone partly due to the wind effect on mixing. The shape of the shelf is the last important factor since hypoxia occurs at intermediate depths (between 5 and 50 m) on broad shelves (Gulf of Mexico and ECS). Shallow estuaries with low residence time such as the Pearl River estuary during the summer wet season when mixing and flushing are dominant features, or deeper shelves, such as the Gulf of Lion off the Rhone show little or no hypoxia. (c) 2008 Elsevier Ltd. All rights reserved. (Less)

232 citations