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.
In this paper, the application of a homemade Nafion and Co(Salen) modified platinum microelec-trode and an ISO-NOPMC microsensor (World Precision Instruments, USA ) to measure nitric oxide in natural seawater is reported. These two microelectrodes are suitable for the measurement. In natural seawater, the sensitivity and stability of the ISO-NOPMC microsensor are higher than that of the homemade Nafion and Co(Salen) modified platinum microelectrode.
This article discusses the patterns of NO effect on marine phytoplankton growth from chemical perspective.The experimental results of four algae,which are Platymonas hal-golandica var.tsingtaoensis,Platymonas subcordiformis,Skeletonema costatum and Nitzschia closterium farma minutissima,are as follows:(i) In f/2 medium or f/50 medium,the growth of these four algae was obviously promoted or inhibited when nitric oxide of different concentrations was added once or twice each day during the cultivation;(ii) The NO effects on the growth of marine phytoplankton are in normal distribution.Different phytoplankton has different optimum NO concentration,which is consistent with the influence of NO on the growth of high plants;(iii) The effect of NO on Platymonas halgolandica var.tsingtaoensi,which is a food alga,is different from that on the red tide algae Skeletonema costatum and Nitzschia closterium farma minutis-sima.The authors put forward a new opinion that every alga has its own NO threshold concen-tration.All the above results may provide new clues to understand the formation of red tide.
ZHANG Zhengbin LIN Cai LIU Chunying XING Lei WU Zhenzhen SUN Feng
This article studied nitric oxide (NO) effect on the growth of Chaetoceros curvisetus in chemistry for the first time. Nitric oxide was added into the media with 4 different nutrient concentrations f/2, f/50, f/100, and f/200 when the alga was growing. The growth of C. curvisetus could be obviously promoted or inhibited during the cultivation process in NO enriched media of different concentrations. The growth curve in such media showed a sharp single peak that is the optimal NO concentration for the alga growth, which is consistent with the influence of NO on the growth of high plants. In addition, C. curvisetus can produce NO by itself during the growth. Therefore, using NO could effectively regulate the algae growth, which is important in real tide control and remediation.
Surface water can be divided into three layers from top downward: surface microlayer (SML, thickness≤50 μm), subsurface layer (SSL, ≈25 cm) and surface layer (SL, 1–5m), among which the SML plays an important role on sea-air interaction because of its unique physical-chemical property. Carbon dioxide system including DIC (dissolved inorganic carbon), Alk (alkalinity), pH and pCO2 (partial pressure of CO2) in multilayered waters of the Yellow Sea was studied for the first time in March and May 2005. The results show that: DIC and Alk are obviously enriched in SML. The contents of DIC, Alk and pCO2 become lower in turn from SML, SSL to SL, higher in March and lower in May, whereas for pH it was opposite. The relationship between DIC and Alk is clearly positive, but negative between pH and pCO2. Meanwhile, pCO2 and temperature/salinity is also in positive relation, pCO2 decreases with latitude increase. DIC and Alk show a similar variation trend with the maximum at 02:00–03:00, but pH and pCO2 show an opposite pattern. In addition, the distribution patterns are similar to each other in the three layers. The Yellow Sea is shown to be a sink of atmospheric CO2 in spring by two methods: (1) comparing pCO2 in seawater and atmosphere; (2) turning direction of “pH-depth” curve. Calculation on the base of pCO2 data in SML in four models shows that carbon flux in spring in the area was about -6.96×106 t C.
