Preliminary study on the distribution of nutrients, organic matter, trace metals in sea surface microlayer in Xiamen Bay and Jiulong Estuary

The enrichment of nutrients (Noa-, Noa-, PO43-), suspended particles, organic matter (POC, PON,DOC) , and trace metals (Cu, Ni, Cd) was determined in the sea surface microlayer of Xiamen Bay and Jiulong Estuary. The mean enrichment factors ([Xi]microlayer/[Xi ]15cm in depth) mostly ranged between 1 . 0 and 2. 0. The dissolved forms were the major forms of the components measured, the enrichment of dissolved organic matter and suspended particles could lead to the changes in the total amount and speciation of nutrients and trace metals. No correlation was observed between sample concentrations, speciation, enrichment factors and sample locations. However, some evidence shows that these parameters are correlated with sea state, indicating the complexity and dynamic nature of the sea surface microlayer.

Viscosity of Sea Surface Microlayer in Jiaozhou Bay and Adjacent Sea Area

This study on the temporal and spatial variability of the viscosity and some chemical parameters in the sea surface microlayer (SML), the relationship between the viscosity and chemical parameters, and the influence of the viscosity on the mass transfer coefficient ( K ) in the flux of materials through the air sea interface revealed that: The values of viscosity and some chemical parameters in the SML are higher than those in the sub surface layer (SSL), and at daytime are higher than those at night. The viscosity has positive corelation with chemical oxygen demand (COD), dissolved organic carbon (DOC) and salinity. The "SML effect" on K need not be considered because the SML effect on materials concentration is so small.

Study on Dissolved Trace Metals in Sea Surface Microlayer in Daya Bay

Glass-plate sampling during 1988-1999 in Daya Bay and suitable corresponding analytical methods were used for the measurement of dissolved trace metals, dissolved organic carbon, biological oxygen demand, chemical oxygen demand, salinity of the sea surface microlayer and subsurface water. Apparent enrichment mechanism and diurnal variation have been revealed for dissolved trace metals in the microlayer in Daya Bay. The more dissolved organic matter was enriched in the sea surface microlayer, the more dissolved trace metals were enriched in the layer. The organic matter played an important role in the enrichment process. The diurnal variations of dissolved trace metals showed that their concentration was apparently inversely related to the tide activity that the concentration was low during rising tide, but high during falling tide. The behavior of dissolved trace metals expressed by the diurnal variation was clearly opposite to that of salinity.

ZOOPLANKTON COMMUNITY STRUCTURE OF THE SEA SURFACE MICROLAYER NEAR NUCLEAR POWER PLANTS AND MARINE FISH CULTURE ZONES IN DAYA BAY

The authors’ surveys in May-June 1999 (two cruises) at six sampling stations near nuclear power plants (NPP) and marine fish culture zones in Daya Bay, Guangdong, revealed species composition, densities and body-size of the sea surface microlayer (SM) zooplankton (>35 μm). Results showed that protozoans and copepod nauplii were the predominant components, accounting for 65.40% to 95.56% of total zooplankton in abundance. The size-frequency distributions showed that the frequency of micro-zooplankton (0.02-0.2 mm) reached 0.8235. The SM zooplankton community structure revealed in the present study was quite different from that revealed by investigations in the 1980s in Daya Bay. Difference of sampling method has important influence on the obtained zooplankton community structure. SM zooplankton consisted of micro- and mesozooplankton (0.2-2.0 mm), with micro-zooplankton being predominant. Some possible cause-effect relations between the zooplankton community structure and mariculture, nuclear power plants cooling systems and sampling method are discussed.

BIOLOGICAL AND CHEMICAL STUDIES OF SEA- SURFACE MICROLAYER (SML) IN DAYA BAY, CHINA IIA.BIOLOGICAL AND CHEMICAL CHARACTERISTICS OF THE SML AND THE CORRELATION AMONG THEM

Two cruises for multi discipline investigation were conducted in October and November, 1998 in Daya Bay to collect: (1) samples from five levels including sea surface microlayer (SML), subsurface (SSL), surface, body (mid column) and bottom water; and (2) observational data on chlorophyll a and nutrients, and important factors such as turbidity, BOD, COD, TN, TP and phytoplankton. Results showed that there was no enrichment of chlorophyll a in the SML, but quite notable enrichment of some organic matter and nutrients. Compared with the findings in earlier researches, PO 4 P and SiO 3 Si have decreased, and the N/P ratio has increased obviously to even more than 100 in the SML. It is concluded preliminarily that PO 4 P and SiO 3 Si mainly determine phytoplankton growth in Daya Bay at present.

Determination of copper complexation in surface microlayer of Daya Bay and Jiaozhou Bay

Copper complexing ligands concentration (C C) and conditional stability constant of the sea surface microlayer (SML) and subsurface layer (SSL) samples, collected from Daya Bay of Guangdong Province and Jiaozhou Bay of Shandong Province, were determined by anodic stripping voltammetry (ASV) technique. C C of Daya Bay in the SML ranged from 6.19×10-7 to 3.52×10-7 mol/L. C C of Jiaozhou Bay in the SML ranged from 5.30×10-7 to 3.03×10-7 mol/L in August 1998 and from 3.46×10-7 to 1.36×10-7 mol/L in May 2000. The C C concentrations were higher in all surface microlayer samples, compared with corresponding subsurface samples. The average enrichment factors of copper complexation in the SML observed above were 1.58, 1.41 and 1.56, respectively. The enrichment of C C concentration in the microlayer demonstrated that organic ligands had certain buffer action on the toxicity of the enriched trace metals in the same layer. Conditional stability constants of the SML in Jiaozhou Bay were lower than those of the SSL; however, it showed just opposite for Daya Bay. BOD (biological oxygen demand) and COD (chemical oxygen demand) indicated the organic matter content, also showed enriched in the SML. C C had an obvious relationship with BOD or COD.

Response of Phytoneuston Community to Organic Nitrogen and Phosphorus Revealed by HPLC-Pigments Method

The sea surface microlayer(SML)is the thin boundary layer between the ocean and the atmosphere.Phytoplankton community in the SML is known as phytoneuston and has a different community structure and biomass from the phytoplankton of the underlying bulk water.In this study,water samples were collected from the SML of Daya Bay in southern China in September,October,and December of 2013.Algal growth potential(AGP)tests were conducted by adding different forms of nitrogen(N),phosphorus(P)and silicate(Si).Phytoneuston grew well with both inorganic and organic nutrients,and showed comparable community structure after nutrient addition.A total of 16 pigments were analyzed in the SML samples collected from Daya Bay in this study.Phytopigments were dominated by the cyanobacteria-diagnostic pigment(zeaxanthin,Zea)in September and October,and by diatom-diagnostic pigment(fucoxanthin,Fuco)in December.The concentrations and proportions of Fuco increased greatly after the nutrient addition,and the concentrations and proportions of Zea decreased accordingly.Additionally,the diatom pigment index(DiatDP)increased after nutrient addition,and the prokaryotic pigment index(ProkDP)conversely decreased.The results suggested that massive occurrences of Zea and cyanobacteria are important characteristics of phytoneuston structure in Daya Bay especially in warm seasons,and nutrient addition especially Si addition promoted the growth of diatoms.

Alkaline phosphatase activity in the phosphorus-limited southern Chinese coastal waters

Three fractions of alkaline phosphatase activity(APA),including phytoplankton APA(phyto-APA),bacterial APA(bact-APA),and free-APA,were examined in the sea surface microlayer(SML)and the subsurface water(SSW)from Daya Bay,Guishan Island,and Guanghai Bay of southern China.Relationships between APA and environmental parameters were analyzed.The growth of phytoplankton was significantly limited by dissolved inorganic phosphorus(DIP)in the three sea areas,especially in Daya Bay.TotalAPA ranged between 1.41 and 35.26 nmol/L/hr,and the highest value was found in Daya Bay.The increased APA in Daya Bay was the result of the increase of phytoplankton biomass and the response of phytoplankton to P limitation.Phyto-APA was the main contributor in Daya Bay,while phyto-and free-APA co-dominated in Guishan Island and Guanghai Bay.Bact-,phyto-,and total-APA showed a significant inverse power function relationship with DIP,and 0.2μmol/L was the threshold for DIP on particulates and totalAPA.Pearson correlation analysis suggested that DIP limitation together with high N levels enhanced APA.High water temperature and freshwater input accelerated APA as well.Principal component analysis clearly separated samples from the three sea areas,as well as from the SML and the SSW,which indicated the differences in environmental parameters and APA levels.Our results highlight the influence of phosphorus limitation and environmental parameters on APA.