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Li J.-L.,Beijing Normal University | Li J.-L.,Chinese Research Academy of Environmental Sciences | Li J.-L.,China National Environmental Monitoring Center | Zheng B.-H.,Chinese Research Academy of Environmental Sciences | And 2 more authors.
Research of Environmental Sciences | Year: 2013

Three cruises were conducted in the Yangtze River estuary from April to November in 2009. The density and composition of phytoplankton were determined in water samples collected at thirty sampling sites. Totally 8 phyla, 95 genera and 330 species were identified in these samples. Diatoms and dinoflagellates, especially Skeletonema costatum, were the dominant species at most sites. The abundance of phytoplankton in seawater decreased with the increase of distance from Yangtze River and a bloom was observed in the summer of 2009. By calculating the diversity index (H), Yangtze River transition water has the largest phytoplankton diversity. The maximum value of H in the sampling area occurred in November. Phytoplankton in the estuary of Yangtze River could be divided into four groups and a significant difference of phytoplankton composition was observed in three sampling seasons. CCA ordination analysis indicated that environmental factors play important roles in controlling the phytoplankton community structure, while the controlling factors vary with seasons. The primary factors affecting the structure of diatom community were identified to be CODMn and NO3 --N content in April, to be SiO4 4--Si, NO3 --N and PO4 3--P content in August, and to be PO4 3--P and SiO4 4--Si in November. Contents of NH4 +-N, CODMn, and NO3 --N and the transparency were the main factors affecting the structure of dinoflagellates in April, August and November, respectively. These results indicated that environmental factors play important roles in the seasonal and spatial variations of phytoplankton community structure in Yangtze River estuary, and the major driving factors changed with seasonal changes.

Li J.,Beijing Normal University | Li J.,Chinese Research Academy of Environmental Sciences | Li J.,China National Environmental Monitoring Center | Zheng B.,Chinese Research Academy of Environmental Sciences | And 4 more authors.
Acta Oceanologica Sinica | Year: 2015

A variety of environmental problems have been observed in the Changjiang River Estuary and adjacent coastal area, including eutrophication, harmful algal blooms (HABs), and hypoxia in recent decades. Application of sedimentary biogenic element indicators on the study of paleoenvironment can reconstruct environmental evolution history of waters. Two 210Pb-dated cores were collected from the Changjiang River Estuary (S3) and adjacent coastal area (Z13), and total organic carbon (TOC), total nitrogen (TN), biogenic silicon (BSi), total phosphorus (TP) and phosphorus (P) species were analyzed. Three stages of environmental changes are deduced by the nutrient sedimentary records. First, nutrient concentration increased rapidly since the 1950s, which attributed to agriculture development and overused chemical fertilizers. Second, nutrient concentration kept high and primary production began to promote during the 1960s to 1980s, while diatom abundance and proportion began to decline since the 1970s, accompanied by reduced SiO3 2− concentration and flux from the river. Third, due to several dams and bridges constructed, river runoff and coastal hydrodynamic conditions reduced to a certain extent since the 1990s, which aggravated the unbalance in nutrient structure. Multi-nutrient proxies in sediment can reflect the natural environmental changes as well as influence of human activities. © 2015, The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg.

Li J.L.,Chinese Research Academy of Environmental Sciences | Li J.L.,China National Environmental Monitoring Center | Zheng B.H.,Chinese Research Academy of Environmental Sciences | Liu Y.,Peking University | And 4 more authors.
Science China Earth Sciences | Year: 2015

Recently, environmental pressures along coasts have increased substantially. Classification of estuaries according to their susceptibility to eutrophication nutrient load is a useful method to determine priority management objects and to enforce control measures. Using historical monitoring data from 2007 to 2012, from 65 estuaries, including 101 estuarine monitoring sections and 260 coastal monitoring stations, a nutrient-driven phytoplankton dynamic model was developed based on the relationship among phytoplankton biomass, Total Nitrogen (TN) load and physical features of estuaries. The ecological filter effect of estuaries was quantified by introducing conversion efficiency parameter values into the model. Markov Chain Monte Carlo algorithm of Bayesian inference was then employed to estimate parameters in the model. The developed model fitted well to the observed chlorophyll, primary production, grazing, and sinking rates. The analysis suggests that an estuary with Q/V (the ratio of river flow to estuarine volume) greater than 2.0 per year and ɛ (conversion efficiency ratio) less than 1.0 g C/g N can be classified as less susceptible to TN load, Q/V between 0.7 to 2.0 per year and ɛ between 1.0 to 3.0 g C/g N as moderately susceptible, and ɛ greater than 3.0 g C/g N as very susceptible. The estuaries with Q/V less than 0.7 per year vary greatly in their susceptibility. The estuaries with high and moderate susceptibility accounted for 67% of all the analyzed estuaries. They have relatively high eutrophication risks and should be the focus of environmental supervision and pollution prevention. © 2015, Science China Press and Springer-Verlag Berlin Heidelberg.

Li J.-L.,China National Environmental Monitoring Center | Li J.-L.,Chinese Research Academy of Environmental Sciences | Zheng B.-H.,Chinese Research Academy of Environmental Sciences | Zhang L.-S.,China National Environmental Monitoring Center | And 5 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2016

Eutrophication characteristics and variations were analyzed using four main statistical methods of box-plot analysis, cluster analysis, correlation analysis and principal component analysis, which were conducted based on natural geographic data and water quality monitoring data of 65 estuaries from 2007 to 2012 years in China. The results showed there was significant difference in eutrophication response indicators between the large-scale estuaries and small-scale estuaries. The eutrophication states of large-scale estuaries were more serious. It was also showed DIN, PO4 3--P and COD were the first principal component of eutrophication characteristics, followed as DO and Chl-a for second, and Depth, Tidal and Area for third. In addition, there was significant positive correlation between the Chl-a and TN input (P<0.01), DIN (P<0.01), PO4 3--P (P<0.05), inflow (P<0.01) and temperature (P<0.05), while there was significant negative correlation between chlorophyll a and tidal (P<0.05), salinity (P<0.01) and DO (P<0.01) in estuaries. It indicated the increase in nutrient input was the main factor which resulted in eutrophication symptoms. However, eutrophication state would be adjusted by typological factors and lead to different response characteristics among estuaries. The nutrient conversion efficiencies of estuarine tidal below 2.5m were higher than the ones above 2.5m. It is implied the eutrophication susceptibility to nutrient load could be regulated by changing water residence time, vertical mixing and light conditions. Furthermore, the Chl-a concentration were also influenced by water exchange with offshore area, biological predation and other nutrient forms supply in estuary. The differences and extent of eutrophication among estuaries were determined synthetically by nutrient inputs from human activities, as well as natural attributes of the estuary. © 2016, Chinese Society for Environmental Sciences. All right reserved.

Shen C.,Zhejiang University | Tang X.,Zhejiang University | Yao J.,Zhejiang University | Shi D.,Zhejiang University | And 4 more authors.
Journal of Hazardous Materials | Year: 2010

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were analyzed in bottom ash from municipal solid waste (MSW) incineration in six cities in Zhejiang province, where one-fourth of the MSW incinerators of China are located. Total PAH contents varied from 2222.53 to 6883.91μg/kg. The patterns of PAHs were found to be very similar in all the samples, dominated by three-ring and four-ring PAHs. Total PCB concentrations in bottom ash ranged from 1.00 to 1.31μg/kg, while the coplanar PCBs in the bottom ash were in the range of 0.08-0.52μg/kg. Among PCB congeners, low chlorinated PCBs contributed to the majority of total PCBs. Generally, PAH concentrations in cities with fluidized bed incinerator were less than those in cities with grate furnace incinerator. PAH and PCB levels were affected by both plastic content in MSW incinerator feed and combustion efficiency. However, further study is required to investigate the effect of these two variables deeply, as well as other influencing factors. © 2010 Elsevier B.V.

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