Huasheng Hong

Fate and assessment of persistent organic pollutants in water and sediment from Minjiang River Estuary, southeast China

Persistent organochlorine compounds were analyzed in surface water, porewater and surficial sediment samples from Minjiang River Estuary, which is the first large river in Fujian Province, Southeast of China. The total concentrations of 18 organochlorine pesticides were 214.4-1819, 4541-13,699 ng/l, 28.79-52.07 ng/g in surface water, porewater and sediments (dry weight) respectively, and those of 21 polychlorinated biphenyls (PCBs) in the three phases were: 203.9-2473, 3192-10,855 ng/l, 15.14-57.93 ng/g respectively. The results showed that the concentrations of these selected organochlorine pesticides and PCBs in porewater were higher than those in surface water. It may be due to the fact that these organic hydrophobic pollutants tend to stay in the sediments, and then re-suspend from the sedimentary phase to the upper water. We have analyzed the distribution characteristics of individual organochlorine pesticide components and PCBs, and found that alpha-HCH, DDE, Heptachlor, Endosulfan II, Methoxychlor were the most common organochlorine pesticides contaminants. Considering the groups of HCHs (HCHs=alpha-HCH+beta-HCH+gamma-HCH+delta-HCH) and DDTs (DDTs=DDT+DDD+DDE), the predominance of beta-HCH, DDE in all water, porewater and sediment samples was clearly observed. This observation suggested that beta-HCH was resistant to biodegradation and the DDTs had been transformed to its metabolites, DDE and DDD, of which DDE that was more un-degradable. The PCB congeners containing 3-6 chlorines had the great preponderance in the three phase. These results were compared with those present in other estuaries and harbors. A risk assessment was evaluated for the persistent organic pollutants in the Minjiang River Estuary.

Beneficial effects of Bacillus licheniformis on the intestinal microflora and immunity of the white shrimp, Litopenaeus vannamei

When Bacillus licheniformis was administered to the white shrimp, Litopenaeusvannamei, although the total bacterial counts in the intestinal tract of the shrimp remained constant, Vibrio numbers significantly decreased (Pxa0<xa00.05). Haemocyte counts together with phenoloxidase and superoxide dismutase activities of the shrimp were significantly higher (Pxa0<xa00.05) in treatments than in the control. Thus, administration of B. licheniformis can improve the white shrimps intestinal microflora and its immune ability.

The distribution characteristics of bacterial β-glucosidase activity in Taiwan strait

Twenty stations were established in the near-shore regions of South Fujian Shoal (116 degrees 10-119 degrees 00 E, 21 degrees 20-24 degrees 10 N) on summer and winter cruises during the period from August 1997 and February to March 1998. The distribution pattern of marine bacterial beta-glucosidase activity (beta-GlcA) has been investigated by using fluorogenic model substrate (FMS) technique in order to have better understanding of the beta-GlcA, as well as its relation to marine bacterial biomass, productivity and environmental factors in Taiwan strait. The results showed that: (1) In summer, the average of beta-GlcA at the Southern stations of Taiwan strait was 1.94 nmol/l h. While in winter, the average of beta-GlcA at the Northern stations was 0.86 nmol/l h and the range of variation (0.34-1.89 nmol/l h) was much more narrow than that in summer (0.31-8.1 nmol/l h). (2) According to the carbon conversion factor, the beta-GlcA was 0.14 and 0.062 ugc/l h in summer and winter respectively. These beta-GlcA values were higher than the bacterial production of the two seasons respectively. (3) The beta-GlcA gradually rises from offshore water to near-shore water. (4) The correlation between the beta-GlcA and the bacterial secondary production was not so obvious. (5) The correlation between the section distributions, daily varying of the beta-GlcA and the bacterial production was not obvious. (6) In the surface water, the distribution character of free-state beta-GlcA from bacteria was equal to that of the total beta-GlcA in the whole sea area.