| In this paper, we have investigated the distribution of acrylic acid in coastal waters of China in 2012-2013. The correlations between hydrological parameters and AA were analyzed. We also disscussed the influence of various environmental factors on the distribution of AA. The results as follows:(1) Research on methods of sampling and preservation:in order to optimize the sampling and preservation methods of AA, this study investigated the effects of large-volume filtration on the concentration of AA. We found that AA concentration increased with the increasing of volume filtration. Therefore, the small-volume filtration was collected.In addition, the compare experimental results on samples stored show that frozen samples will increase the concentration of AA, therefore, samples should be kept refrigerated.(2) Research on the Yellow Sea and the South China Sea in summer:we conducted a survey on the Yellow Sea waters in July 2013. As a result,we obtained the spatial distribution of AA concentrations and analysis of the impact of hydrological parameters and Chl-a on AA distribution. The concentrations of AA in the surface water were 5.8-713.0 (154.8) nmol L-1, and showed the characteristics that the higher concentrations obtained inshore. The concentrations of AA and Chl-a were low in the central of the South Yellow Sea due to the affect of the cold water mass. AA/Chl-a ratio is in the range of 0.002-1.30(0.21)mol g-1 and it showed great spatial differences due to the impact of differences in phytoplankton community structure. AA was positively correlated with temperature and DMSPd.We have investigated the concentration distribution of AA in the South China Sea in July 2013 and analyzed the influence of various parameters on AA. AA concentrations was in the range of 0-60.0 (15.6) nmol L-1,with high values mostly appeared in the high latitude which is consistent with previous findings on DMS.In the surface water, AA was positive correlation with DMS whereas present negative correlations with DMSPt and DMSPd. According to the vertical distributions of AA in the South China Sea, AA and Chl-a concentrations show the similar distribution patterns. Subject to the limiting light in the euphotic zone, the highest concentrations are mostly appeared in the upper layer.(3) Research on the Yellow Sea and the East China Sea in autumn:the biogeochemistry of dimethylsulfoniopropionate (DMSP), dimethylsulfide (DMS) and acrylic acid (AA) in the Yellow Sea (YS) and the Bohai Sea (BS) were investigated in November 2013. The concentrations of total DMSP (DMSPt), dissolved DMSP (DMSPd), DMS, and AA in the surface water were 30.71 (1.07-122.50),6.60 (0.85-35.67),1.48 (0.53-5.32) and 42.2 (13.8-352.8) nmol L-1, respectively. The concentrations of DMSPd and AA were positively correlated with the levels of chlorophyll a, suggesting that phytoplankton biomass might play an important role in controlling DMSPd and AA distributions in the study area. Furthermore, the DMS and AA concentrations revealed significant positive relationships with DMSPd concentrations. The ratios of AA/(DMSP+AA) and DMS/AA varied from 37.46% to 98.58% and from 0.36% to 29.71%, with mean values of 80.64% and 7.62% in the surface water. The vertical profiles of DMSP, DMS, and AA were characterized by higher concentrations mostly occurred close to the surface, although the depths of maximum concentrations were not uniform at different stations. Complex hydrographic conditions and terrestrial runoff might also influence spatial variability of DMSP, DMS, and AA in the areas. The consumption rates of DMSPd and the occurrence rates of DMS and AA significantly varied with marine environments.The concentrations of AA in the water of the East China Sea (ECS) were measured in October 2012 and October 2013. The concentrations of AA ranged from 1 to 525 nmol L-1 with average value of 117 nmol L-1 in 2012. AA concentrations significantly higher in coastal waters than in the open sea, except by the influence of terrestrial input, but also because the two sea areas are in centers of Fujian and Zhejiang upwelling. AA/Chl-a ratios decreases from south to north and the linear analysis also shows that AA/Chl-a is positively correlated with temperature. And AA is negatively correlated with the DMS.Four sections from north to south reflects the impacts of the Yangtze freshwater, black tide and Taiwan warm current on the distribution characteristics of AA. The concentrations of AA ranged from 16.03 to 258.58 nmol L-1 with average value of 83.27 nmol L-1 in 2013. AA concentrations were also significantly higher in coastal waters than in the open sea. In the northeast of survey area, AA/Chl-a increases from north to south and from near-shore to off-shore. In the southwest of the east China sea, the radios were gradually increased from inshore to offshore. There were no significant correlations between AA and temperature, salinity, Chl-a concentrations.(4) Comparing the constant of DMSP degradation rate and the constant of DMS or AA production rate outside the bay between two seasons, we get the result that the rate constants of summer were higher than in spring. Similarly, two seasons were compared in the Bay, the results are basically the same except that AA production rate was higher in the spring maybe because the AA degradation rate is also faster in summer. We also discussed the effects of temperature, acidity and size on the biological production and transformation process of DMSP, DMS and AA. Elevated temperature would promote the degradation of DMSPd and the generation of DMS and AA; Acidification and alkalinization of seawater will promote the degradation of DMSP and the promoting effect of alkaline was more apparent; The bigger of the particle size of the filter, the larger DMSPd concentrations decline. |
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