Spatial variation of lipophilic marine algal toxins and its relationship with physicochemical parameters in spring in Laizhou Bay,China

Lipophilic marine algal toxins(LMATs)are produced by some toxigenic microalgae,which pose a serious threat to marine ecosystem and even human health.The occurrence and environmental control factors of LMATs in the surface seawater and phytoplankton in spring in Laizhou Bay in which Huanghe(Yellow)River estuary is included,in Shandong,East China were investigated.Okadaic acid(OA),pectenotoxin-2(PTX2),dinophysistoxin-1(DTX1),pectenotoxin-2 seco acid(PTX2 SA),DTX2,7-epi-PTX2 SA,PTX11,and 13-desmethyl spirolide C(SPX1)were detected from the surface seawater samples,and PTX2,7-epi-PTX2 SA,OA,DTX2,DTX1,PTX2 SA,and PTX11 were discovered in the phytoplankton samples showed a decreasing trend.The concentrations of∑LMATs in the seawater and phytoplankton ranged 2.03-74.38 ng/L on average of 13.72 ng/L and 0.98-479.27 pg/L on average of 50.20 pg/L,respectively.The joint influence of terrigenous input and internal circulation could promote the growth,toxin production,and toxin release of toxin-producing algae,leading to a higher content of LMATs in the bay nearby the Huanghe River estuary in both seawater and phytoplankton.The concentration of LMATs in spring was higher than that in summer,showing obvious seasonal variation.In addition,no significant correlation between most of the physiochemical parameters and LMAT contents in seawater was revealed by correlation analysis except for the positive correlation between DTX2 and chlorophyll a,OA and NH4-N.However,the increase of dissolved inorganic nitrogen content in seawater could enhance the production of OA,DTX1,and DTX2 in phytoplankton due probably to that the inorganic N input could benefit the growth and stimulate toxin production of toxin-producing algae.The result also proved that some PTX2 may be originated from Procentrum spp.and OA,DTXs and part of PTX2 may be originated from Dinophysis spp.

Development of High Efficient and Low Toxic Oil Spill Dispersants based on Sorbitol Derivants Nonionic Surfactants and Glycolipid Biosurfactants

Dispersants, usually blending with several surfactants and a solvent, are used to enhance oil spill dispersion as small droplets in water column. Although there is growing acceptance of dispersants as a counter measure to marine oil spills around the world, the two major issues with the dispersants are their toxicity to marine life and dispersion effectiveness (DE) for crude-oil, especially for heavy oil. To develop more efficient and less toxic dispersants, two kinds of sorbitol derivant nonionic surfactant (polysorbate 85 and sorbeth-40 tetraoleate), two kinds of glycolipid biosurfactants (rhamnolipid and sophorolipid) and less toxic solvent ethylene glycol butyl ether were chosen in this study, and two dispersant formulations were optimized by uniform design methods. Effects of dispersant-to-oil ratio, temperature, salinity and pH on the performance of the two optimized dispersants were investigated. The two dispersants had high dispersion effectiveness (DE) for heavy crude oil, while both dispersants keep high DE at the dispersant-to-oil ratio below 1:25 and the temperature above 5 ℃. In addition, the two dispersants also performed well in a wide range of salinity and pH values. Finally, toxicity tests revealed that the two dispersants showed low toxicity to two kinds of fish (Danio rerio and Microgobius gulosus).