International audienc

Spatial and temporal distributions of nutrients (N and P) and heavy metals (Cu, Zn, Pb and Cd) in the intertidal sediments at Dongtan wetland of the Changjiang River (Yangtze River) Estuary were examined by laying one transect running seaward to landward during January, April, June, August and October of 2005. Total nitrogen (TN) and heavy metal concentrations in the intertidal sediment showed an increasing trend from open bare flat to the high marsh, with the maximum concentrations in the high marsh and the minimum values in open bare flat. In contrast, sediment total phosphorus (TP) concentrations changed little among sampling sites. One-way ANOVA found that there were significantly temporal variations of nutrients and heavy metals concentrations in the intertidal sediment (P <0.05). The concentrations of heavy metals generally showed an increasing trend from January to October. As compared with other large estuaries, heavy metal contamination in the intertidal sediment of the Changjiang River Estuary was relatively low.

In this paper, the acute toxicity of four fuel oils including F120, F180, F380 and No.-20 was evaluated by exposing the marine microalgae Chlorela spp. (Chlorophyta) and Skeletonema costatum (Bacillariophyta) in the fuel oil water accommodated fractions (WAF). The bioassay showed that F180 WAF was the most toxic to both microalgae. The 96 h EC(50) value of F180 WAF for Skeletonema costatum and Chlorela spp. was 9.41 and 13.63 mg/L expressed in concentration of total petroleum hydrocarbons, respectively. WAFs of F120, F180 and F380 were more toxic to Skeletonema costatum than to Chlorela spp. In contrast, No.-20 WAF did not show significant toxicity for both Skeletonema costatum and Chlorela spp.

No abstract

The lethal and sublethal effects of aquatic organisms by crude or fuel oils has been widely investigated, but the potential impacts of crude oils and fuel oils in the Yangtze River Estuary and East China Sea aquatic environments remain unclear. The toxicity of oils and compounds were measured in the sensitive embryonic development of the Large Yellow Croaker (Larmichthys crocea). The EC 50 of hatching rate of embryos of the Large Yellow Croaker by TJ014 and -20 were 112.4 mg/L and 510.8 mg/L, respectively; The LC 50 of after hatched of larvae by TJ014 and -20 were 8.5 mg/L and 156.2 mg/L, respectively. Acute exposures lead to the developmental abnormalities such as bradycardia, spinal curvatures, and reducing somite which is convenient and useful to evaluate the toxicity of oil. According to Values of LC 50 /EC 50 and the degree developmental abnormalities could explain the toxicity of TJ014 was larger than -20. Therefore, these results may be provided some useful proofs to analysis the aquatic environmental risk.